WO2008056791A1 - Lithium-ion secondary battery - Google Patents

Lithium-ion secondary battery Download PDF

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Publication number
WO2008056791A1
WO2008056791A1 PCT/JP2007/071841 JP2007071841W WO2008056791A1 WO 2008056791 A1 WO2008056791 A1 WO 2008056791A1 JP 2007071841 W JP2007071841 W JP 2007071841W WO 2008056791 A1 WO2008056791 A1 WO 2008056791A1
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Prior art keywords
positive electrode
secondary battery
lithium ion
ion secondary
negative electrode
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PCT/JP2007/071841
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French (fr)
Japanese (ja)
Inventor
Ryuji Shiozaki
Asao Iwata
Satoko Kaneko
Nobuo Ando
Masahiko Taniguchi
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Fuji Jukogyo Kabushiki Kaisha
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Application filed by Fuji Jukogyo Kabushiki Kaisha filed Critical Fuji Jukogyo Kabushiki Kaisha
Priority to EP07831572A priority Critical patent/EP2104174A4/en
Priority to JP2007556451A priority patent/JPWO2008056791A1/en
Priority to US12/298,345 priority patent/US20100173184A1/en
Publication of WO2008056791A1 publication Critical patent/WO2008056791A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G31/00—Compounds of vanadium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—Polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/88—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by thermal analysis data, e.g. TGA, DTA, DSC
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to battery technology, and is particularly effective for non-aqueous lithium secondary batteries.
  • a lithium ion secondary battery is a so-called locking in which, after battery assembly, charging is performed to supply lithium ions from a lithium-containing metal oxide of a positive electrode to the negative electrode, and in discharging, the lithium ions of the negative electrode are returned to the positive electrode. It is a chair type battery.
  • the Coulomb efficiency of the positive electrode material is higher than the Coulomb efficiency of the negative electrode material.
  • the initial capacity of the battery after assembly is the product of the charge amount and the coulomb efficiency of the negative electrode. That is, the initial capacity of the battery is determined by the Coulomb efficiency of the negative electrode.
  • positive electrode materials include a wide range of oxide-type compounds represented by LiCoO, LiNiO, LiMn 0, or olivine compounds represented by LiFePO.
  • the positive electrode material contains lithium ions. Therefore, it can be easily operated as a secondary battery simply by combining with the negative electrode.
  • the lithium-containing metal oxide is used in the oxidation-reduction reaction! Less than 1 mole of lithium ion utilization per mole of metal oxide. Therefore, we cannot expect a high level discharge capacity.
  • vanadium oxide can dope or dedope several moles of lithium ion per mole of vanadium oxide. Therefore, it may become a positive electrode material for a large capacity lithium ion secondary battery.
  • Patent Documents 1 and 2 disclose a technique using xerogel synthesized by gelling vanadium pentoxide (V 0) as a positive electrode active material. However, all of them use an active material in a gel state in which crystals are sufficiently developed. Furthermore, it is a thin film electrode in which an active material is directly formed on a current collector. Therefore, the electron conductivity is low and the characteristics cannot be fully exhibited.
  • Patent Documents 1 and 2 have a polymer solid electrolyte type battery configuration using metallic lithium. This avoids a short circuit due to the precipitation of dendrite lithium. However, even if such a polymer solid electrolyte is used, it is difficult to suppress dendrite precipitation after a long cycle. For this reason, the configurations disclosed in Patent Documents 1 and 2 are difficult to use as a large-capacity power source.
  • Patent Document 3 discloses a secondary battery using a carbon negative electrode and a liquid electrolyte. In this method, a positive electrode and a lithium electrode are combined, and the positive electrode is doped with lithium ions in advance, and then the lithium electrode and the carbon negative electrode are combined to produce a battery.
  • Non-Patent Document 1 discloses a technique related to charge and discharge in a similar battery system that operates at a positive electrode operating potential of 2.5 V or more.
  • LiV 0 is chemically synthesized by heat treating V 0 and a lithium salt. Thereby, lithium ions are supplemented in advance.
  • Patent Document 1 Japanese Patent No. 3108186
  • Patent Document 2 Japanese Patent No. 31 15448
  • Patent Document 3 Japanese Patent Publication No. 5-80791
  • Patent Document 4 Japanese Patent Laid-Open No. 05-198300
  • Non-Patent Literature l Joumal of Power Sources 54 (1995) 146-150
  • the above-described lithium ion secondary battery technology has the following problems. That is, in the technique of Patent Document 3, the lithium ion supply source is only from the positive electrode. Therefore, it is restricted by the charge / discharge efficiency of the negative electrode, and high discharge energy cannot be extracted. In addition, because there is a lithium ion doping process and an electrode recombination process, productivity is low when actually manufacturing batteries.
  • Non-Patent Document 1 when operating at 2.5 V or higher, it is difficult to achieve a high energy density with low utilization of the positive electrode.
  • An object of the present invention is to provide a lithium ion secondary battery that is easy to manufacture and has a high energy density.
  • the present inventors have conducted intensive research. As a result, the positive electrode and the negative electrode of the lithium ion secondary battery are within a certain operating potential range. As a result, the present invention has been found.
  • a positive electrode, a negative electrode, and an electrolyte solution comprising a lithium salt and an aprotic organic solvent, and a positive electrode active material strength S
  • a material capable of reversibly doping lithium ions and / or anions Lithium ion secondary battery made of a material that can be reversibly doped with lithium ions.
  • the positive electrode and negative electrode potentials after short-circuiting the positive and negative electrodes are 0.5% on the basis of metal lithium (vs. Li / Li +). It was made to be V or more and 2.0V or less.
  • a lithium ion secondary battery having a high energy density is provided by setting the operating potential of the positive electrode and the negative electrode in the range of 0.5 V or more and 2.0 V or less in a non-aqueous lithium ion secondary battery.
  • a lithium ion secondary battery having a high energy density exceeding an energy density power of 3 ⁇ 400 Wh / kg per battery weight is provided.
  • FIG. 1 is an explanatory diagram showing a situation of an operating potential of a lithium ion secondary battery of the present invention.
  • FIG. 2 is an image diagram of an amorphized gel schematically showing a layered crystal structure with a short layer length used in the present invention.
  • FIG. 3 is an image diagram of gelation schematically showing a layered crystal structure having a long layer length different from that used in the present invention.
  • FIG. 4 is an explanatory diagram showing an X-ray diffraction pattern of a positive electrode active material used in the present invention.
  • FIG. 5 is a flow diagram of a method for producing a positive electrode active material used in the present invention.
  • FIG. 6 is a flowchart of a method for producing a positive electrode active material used in the present invention.
  • FIG. 7 is a drawing-substituting photograph of a positive electrode active material used in the present invention by a transmission electron microscope (TEM).
  • TEM transmission electron microscope
  • FIG. 8 is an explanatory view schematically showing a schematic configuration of a laminated lithium ion secondary battery of the present invention.
  • FIG. 9 is an explanatory view schematically showing a schematic configuration of a wound type lithium ion secondary battery of the present invention.
  • FIG. 10 is an explanatory view schematically showing a schematic configuration of a foldable lithium ion secondary battery of the present invention.
  • FIG. 11 is a drawing-substituting photograph of a positive electrode active material used in the present invention by a transmission electron microscope (TEM).
  • TEM transmission electron microscope
  • FIG. 12 is an explanatory diagram showing the effect of the present invention in a tabular format together with a comparative example.
  • the present invention This is a technology related to muon secondary batteries.
  • the present inventor has found that the positive electrode and the negative electrode of the lithium ion secondary battery as described above exhibit a high energy density when they are within a certain operating potential range.
  • a lithium ion secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution composed of a lithium salt and a non-protonic organic solvent.
  • the positive electrode active material is a metal oxide or an organic compound exhibiting redox activity.
  • the negative electrode active material strength S is a material that can be reversibly doped with lithium ions.
  • the positive and negative electrode potentials after short-circuiting the positive and negative electrodes are set to 0.5 V or more and 2.0 V or less on the basis of metallic lithium (vs. Li / Li +). This can increase the energy of the lithium-ion secondary battery.
  • Examples of the organic compound exhibiting redox activity include acetylene, aniline, tetrathionaphthalene, thiophene derivatives, and polymers thereof.
  • FIG. 1 shows a potential profile of a lithium ion secondary battery.
  • the point at which the curve of the force, the positive electrode potential, and the negative electrode potential curve intersect is the potential of the positive electrode and the negative electrode during 0 V discharge when both electrodes are short-circuited.
  • the potential of the positive electrode and the negative electrode is 0.5 V or more and 2.0 V or less on the basis of metal lithium ion (vs. Li / Li +). This is one major feature of the present invention. Such a range is indicated by an arrow in the figure.
  • a lithium ion secondary battery for example, it has a layered crystalline material as a positive electrode active material, and the layered crystalline material contains fine crystalline particles having a layer length of 30 mm or less not containing 0. It is preferable to use an electrode material characterized by having it. Furthermore, as a negative electrode material, easy It is preferable to use graphitized carbon material (soft carbon), graphite, or a mixture of graphitizable carbon material and graphite.
  • a battery configuration of a lithium ion secondary battery for example, a cell configuration in which positive electrodes and negative electrodes are alternately stacked via a separator and then wound, folded, or stacked in three or more layers is used. I prefer to do it.
  • the positive electrode current collector and the negative electrode current collector are provided with through holes that penetrate from the front surface to the back surface.
  • the negative electrode, or the positive electrode, or the negative electrode and the positive electrode are previously doped with lithium ions by electrochemical contact with metallic lithium.
  • dope means occlusion, support, adsorption or insertion, and refers to a phenomenon in which lithium ions and / or anions enter the positive electrode active material, or a phenomenon in which lithium ions enter the negative electrode active material.
  • De-doping means release and desorption, and refers to a phenomenon in which lithium ions or anions are desorbed from the positive electrode active material, or a phenomenon in which lithium ions are desorbed from the negative electrode active material.
  • anion doping means that an anion of a supporting salt contained in an electrolyte is doped when a conductive polymer such as polyacetylene or polyaniline is used on the positive electrode side.
  • a conductive polymer such as polyacetylene or polyaniline
  • CF SO-, C F SO-, (CF SO) N-, (CF SO) C-, BF-, PF-, CIO- are doped.
  • the lithium ion secondary battery of the present invention having such a configuration will be described in further detail below.
  • the active material for the positive electrode used in the present invention for example, an oxide type compound group represented by LiCoO, LiNiO, and LiMn 0 used in a conventional lithium-ion secondary battery, or an olivine compound group represented by LiFePO is used. Is possible. Or layered crystalline material
  • the state of the layered crystalline substance in the present invention refers to a crystal structure having a layer length of 30 nm or less or a crystal structure having a layer length of 30 mm or less from a microscopic viewpoint observed on the order of ⁇ or less. It means a state where an amorphous structure coexists. When such a state is viewed from a macroscopic viewpoint, such as that obtained by X-ray diffraction analysis, which is larger than nm and is observed on the order of ⁇ m or more, an apparently amorphous structure in which crystal structures are randomly arranged is observed. Is done.
  • the layer length of the layered crystalline substance is shortened (miniaturized). For example, a layered crystal state with a long layer length is divided, and a layered crystal state with a short layer length appears.
  • Such a state is a novel structure that cannot be realized in an amorphous state. By stopping the progress of the amorphization halfway, the above state, that is, a layered crystal state with a short layer length can exist.
  • FIG. 2 schematically shows a layered crystal state having a short layer length L1 according to the present invention, that is, an apparent amorphized state.
  • a so-called short-period structure in which the layer length L1 repeats with a short period on average forms a layered crystal structure.
  • the apparently amorphized state according to the present invention a plurality of layered crystals having a short period structure are thus assembled.
  • the layered crystal state according to the present invention having a short layer length is used as, for example, an electrode active material of a battery
  • chemical species such as ions involved in the reaction of the battery enter and exit between layers in the layered crystal state. It becomes easy.
  • ions doped between layers have a short layer length, so that their diffusion path is short and they are easily diffused.
  • the layer with charge / discharge characteristics has excellent cycle resistance and the like.
  • the length of the layer length is particularly important.
  • a layer length affects the length of a path through which ions pass directly when ions enter and exit.
  • the portion other than the layer length for example, the length in the thickness direction of the layer of the layered crystal structure may be reduced as the average crystal grain becomes smaller.
  • the layered crystal state having a short layer length is preferably produced by using vanadium oxide as a raw material, dissolving it with hydrogen peroxide 0) or an alkali salt, and further solidifying the solution. It is possible.
  • the dissolved vanadium oxide solution is acidic.
  • Alkali salt When used, it exhibits alkalinity.
  • lithium ions When lithium ions are used as the cation source for the alkali salt, lithium ions can be doped into the vanadium oxide at the synthesis stage.
  • the lithium ion source for example, water-soluble lithium sulfide, lithium hydroxide, lithium selenide, lithium telluride, or the like can be used.
  • the power S is to use at least one lithium compound selected from the group of such lithium compounds as a water-soluble lithium ion source.
  • a monomer corresponding to the sulfur-containing organic conductive polymer may be mixed with the active material. However, it is desirable to remove the monomer corresponding to the sulfur-containing organic conductive polymer as the final positive electrode active material. Although details are unknown, the sulfur-containing organic conductive polymer is functioning in maintaining the oxide composition during the synthesis reaction of vanadium oxide, but the performance as an active material is considered to be low.
  • the active material thus obtained is mixed with a binder such as polyvinylidene fluoride (PDVF), preferably with conductive particles, to obtain a positive electrode material.
  • a binder such as polyvinylidene fluoride (PDVF)
  • PDVF polyvinylidene fluoride
  • This is applied on a conductive substrate (current collector) to produce a positive electrode.
  • the layer of the positive electrode material for the non-aqueous lithium ion secondary battery is formed to a thickness of 10 to 200 ⁇ m, for example.
  • the conductive particles include conductive carbon (conductive carbon such as ketjen black), metal such as copper, iron, silver, nickel, palladium, gold, platinum, indium, tungsten, indium oxide, oxide There are conductive metal oxides such as tin.
  • the conductive particles may be contained in an amount of 1 to 30% of the weight of the metal oxide.
  • a conductive substrate having conductivity at least on the surface in contact with the positive electrode material can be used.
  • a substrate is a metal, conductive metal oxide Or a conductive material such as conductive carbon.
  • copper, gold, aluminum, an alloy thereof, or conductive carbon is preferable.
  • the base is formed of a non-conductive material, it is necessary to coat the base with a conductive material.
  • a layered crystalline substance having a short layer length which is effective as a positive electrode material for a non-aqueous lithium secondary battery, is manufactured through a manufacturing process as shown in the flowchart of FIG.
  • step S110 vanadium pentoxide is prepared as a layered crystalline material.
  • a water-soluble lithium ion source is prepared in step S120, and a monomer corresponding to sulfur-containing organic conductivity is prepared in step S130.
  • step S140 the monomers corresponding to vanadium pentoxide prepared in steps S110, S120, and S130, the water-soluble lithium ion source, and the sulfur-containing organic conductive polymer are suspended in water. Amorphization begins with force and suspension.
  • the water-soluble lithium ion source for example, lithium sulfide or lithium hydroxide can be used.
  • 3,4-ethylenedioxythiophene can be used as the monomer corresponding to the sulfur-containing organic conductivity.
  • step S150 The suspension is heated to reflux in step S150 for a predetermined time. After heating and refluxing in step S150, the solid content is removed from the heated and refluxed suspension by filtering in step S160. The filtrate from which the solid content has been removed is concentrated in step S170. After concentrating the filtrate, it is dried in step S 180 by vacuum drying or the like.
  • step S190 the particles are pulverized to a predetermined particle size by a ball mill or the like, and classified by sieving. In this way, a layered crystal structure powder having a short layer length of vanadium pentoxide is obtained. Such layered crystal structure powder is used as an active material of the positive electrode material.
  • the heating temperature needs to be less than 250 ° C. If it exceeds 250 ° C, the layered crystals with a short layer length change, which is not preferable.
  • a layered crystalline substance having a force and such a short layer length can be manufactured by a manufacturing force S as shown in the flow diagram of FIG.
  • step S210 for the positive electrode material of the non-aqueous lithium ion secondary battery.
  • Synthesize active material A necessary material is mixed with water and heated to reflux for a predetermined time to synthesize an active material soluble in water.
  • the active material suspension for the positive electrode material synthesized in this way is filtered, and in step S220, the spray drying method is applied.
  • the active material for the positive electrode material can be made into a fine spherical particle positive electrode material powder.
  • the positive electrode material powder is a spherical water-soluble particle having an average particle diameter of 0.1 m or more and 20 m or less.
  • the active material once produced without using the spray drying method may be pulverized to a predetermined particle size with a ball mill or the like and classified by sieving.
  • the spraying and drying method it is possible to save the troubles of pulverization, classification, etc., and further, the obtained particles become fine spherical particles having a fine average particle diameter of submicron or less. In this way, a layered crystal structure powder of vanadium oxide such as vanadium pentoxide having a short layer length is obtained.
  • the crystal grains observed in the cross section include a layered crystal state having a layer length of 30 ⁇ m or less in an area ratio of 30% or more in the cross section.
  • crystal grains in an arbitrary cross section are contained in an area of 30% or more.
  • the energy density of the lithium ion secondary battery having such a structure is better than that of the case where it includes a layered crystal structure having a layer length exceeding the crystal particle force of> 0 nm. Further, it may be contained in an area% of 30% or more and less than 100%. The upper limit is valid up to a value close to 100%. In the case of 100%, there is no amorphous state in the crystal particles, and only the layered crystal state.
  • the minimum layer length of the layered crystal structure is preferably 1 mm or more. If the layer length of the layered crystal is less than 1 mm, the layered structure cannot be maintained, so lithium ions cannot be doped or dedoped, and the capacity cannot be taken out. On the other hand, if the layer length exceeds 30 mm, the crystal structure collapses due to charge and discharge, resulting in poor cycle characteristics. Therefore, the layer length is preferably 1 nm or more and 30 nm or less. More preferably, the layer length is 5 nm or more and 25 nm or less. FIG.
  • Fig. 7 shows a layered crystal state of the positive electrode active material used in the present invention having a layer length of 1 nm or more and 30 nm or less as a transmission electron micrograph used as a drawing substitute photo.
  • Fig. 7 shows the case of lithium vanadium pentoxide, especially when a layered crystal state of 5 nm or more and 25 nm is observed.
  • a non-aqueous lithium ion secondary battery is formed by forming a positive electrode using such an active material.
  • the non-aqueous lithium ion secondary battery includes the positive electrode, the negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode.
  • a commonly used material for a lithium ion secondary battery can be used for the negative electrode.
  • the power and curable materials include lithium-based metal materials such as lithium metal lithium alloys (eg, Li-Al alloys), intermetallic compound materials of metals and lithium metals such as tin-cathenium, and lithium nitride. And a lithium intercalation carbon material.
  • Lithium salts such as LiPF and LiCIO can be used.
  • the solvent that dissolves power and electrolytes can be used.
  • non-aqueous solvent chain carbonates, cyclic carbonates, cyclic esters, nitrile compounds, acid anhydrides, amide compounds, phosphate compounds, amine compounds, and the like can be used.
  • a solution obtained by dissolving the above electrolyte in a non-aqueous solvent can be used.
  • a polymer gel (polymer gel electrolyte) containing a force, electrolyte solution can be used.
  • Such a non-aqueous lithium secondary battery has a configuration as shown in FIG. 8, for example. That is, in the nonaqueous lithium secondary battery 10, the negative electrode 1 and the positive electrode 2 face each other with the separator 3 interposed therebetween.
  • a negative electrode active material is provided in a layered manner on a substrate surface as a current collector.
  • a positive electrode active material is provided in a layered manner on a substrate surface as a current collector.
  • a plurality of such negative electrodes 1 and positive electrodes 2 are laminated via separators 3 as shown in FIG.
  • the upper and lower ends are stacked in the vertical direction, and the negative electrode 1 is formed at the upper and lower ends.
  • Metallic lithium 4 is laminated on the negative electrode 1 formed on the upper and lower ends via a separator 3.
  • the outside of the metallic lithium 4 is covered with a copper mesh 5 as a current collector! Not shown! / ⁇ 1S
  • a copper mesh 5 as a current collector! Not shown! / ⁇ 1S
  • Such a stacked electrode group is provided in a non-aqueous solvent in which the electrolyte is dissolved.
  • the separator 3 is impregnated with a non-aqueous solvent in which the electrolyte is dissolved.
  • the configuration of the non-aqueous lithium ion secondary battery may be other configurations.
  • it may be a wound or folded configuration.
  • the configuration shown in FIG. 9 is a wound configuration.
  • the configuration shown in FIG. 10 is a folded configuration.
  • the positive electrode material developed in the present invention can be doped with several moles of lithium ions per mole of the positive electrode material. However, beyond a certain amount, the dedoping ability is significantly reduced. This threshold is up to 1.45V for lithium metal. Below this, capacity degradation proceeds. If it is more than this, it is possible to achieve both high charge / discharge capacity and cycle performance. Preferably it is 1.45V or more to 2V, more preferably 1.5V to 1.9V.
  • Preparation of positive electrode active material In this example, in step S210 of FIG.
  • composition of this powder was determined from TG (Thermobalance, Thermo-Gravimetry). V 0 -0.3H Ou.
  • Fim lithium metal was placed in two locations, upper and lower, to form a pole group consisting of a positive electrode, a negative electrode, metallic lithium, and a separator.
  • the metallic lithium current collector and the negative electrode current collector were welded.
  • Lithium ion doping step After the battery prepared as described above was left for 20 days
  • Charging / discharging test A charging / discharging cycle test was performed using the remaining one-cell battery. 0 charge It was terminated after 30 hours with a constant current and constant voltage (CC CV) charging method of 4.1V at .1C. The discharge was a constant current (CC) discharge method that ended when it reached 0V at 0.05C. After charging and discharging three times under the above conditions, the operating potentials of the positive electrode and the negative electrode were determined from the reference electrode. Both were 1.5V based on metallic lithium.
  • CC CV constant current and constant voltage
  • the discharge capacity at this time was 13.5 Ah.
  • the configuration of the positive electrode and the negative electrode was the same as in Example 1, and the thickness of the metallic lithium disposed at the upper and lower two locations on the outermost part of the electrode laminate unit was changed to 490 am.
  • battery cells were constructed in the same manner as in Example 1, and two cells were produced. When the cell was disassembled after being left for 20 days, all of the lithium metal had disappeared, so it was confirmed that a predetermined amount of lithium ion was previously doped into the negative electrode.
  • a charge / discharge cycle test was performed using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen). Discharging was a constant current (CC) discharging method that ended when it reached 0 V at 0.05C.
  • CC CV constant current constant voltage
  • the configuration was the same as Example 1 except for the configuration of the positive electrode, the configuration of the negative electrode, and the configuration of the thickness of metallic lithium.
  • a lithium ion secondary battery was constructed using the positive electrode and the negative electrode.
  • Such a battery configuration is the same as that of Example 1 except that the thickness of the metallic lithium disposed at the upper and lower two positions on the outermost part of the electrode stack unit is changed to 85 m. In this way, two battery cells were produced. When the cell was disassembled after being left for 20 days, all of the lithium metal disappeared and it was confirmed that a predetermined amount of lithium ions had previously been occluded in the negative electrode.
  • a charge / discharge cycle test was performed using the remaining one-cell battery. Charging was completed after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen at 3.0. Discharge was 3.0 at 0.05C.
  • CC CV constant current constant voltage
  • the discharge capacity after charging and discharging three times under the above conditions was 5.4 Ah.
  • this was allocated based on the battery mass excluding the reference electrode and converted per battery weight, it was 157 Wh / kg-cell.
  • the positive electrode negative electrode operating potential was determined from the reference electrode, and both were 0.5 V based on metallic lithium.
  • Preparation of positive electrode active material In this example, 200 g of vanadium pentoxide, 30 g of lithium sulfide (Li2S) and 3,4-ethylenedioxythiophene (EDOT) lOOg were suspended in 5 liters of water for 24 hours. The mixture was heated and stirred under reflux. After completion of the stirring, suction filtration was performed to remove the solid content. This solid was a polymer of sulfur and 3,4-ethylenedioxythiophene.
  • Li2S lithium sulfide
  • EDOT 3,4-ethylenedioxythiophene
  • a positive electrode paste was prepared with the same composition as in Example 1, and applied to both surfaces of an aluminum current collector having through-holes to produce a positive electrode having a thickness of 175 m.
  • Lithium ion doping step The battery prepared as described above was allowed to stand for 20 days, and then one cell was disassembled. Since all of the metallic lithium had disappeared completely, it was confirmed that the required amount of lithium ions was previously doped into the negative electrode.
  • Comparative Example 1 is the same as in Example 1 except that the lithium ion secondary battery configured in Example 1 above was changed to 420 am in the thickness of the metallic lithium disposed at the upper and lower two positions on the outermost part of the electrode stack unit. Similarly, two battery cells were produced. After leaving for 20 days, 1 cell was disassembled. Since all of the metallic lithium had disappeared completely, it was confirmed that a predetermined amount of lithium ions had previously been occluded in the negative electrode.
  • a charge / discharge cycle test was conducted using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen). Discharging was a constant current (CC) discharging method that ended when it reached 0 V at 0.05C.
  • CC CV constant current constant voltage
  • Example 2 a battery was constructed using the positive electrode in Example 2 and the negative electrode in Example 1.
  • Two battery cells were produced in the same manner as in Example 1, except that the thickness of the lithium metal disposed at the upper and lower two locations on the outermost part of the electrode laminate unit was changed to 350 m. After leaving it for 20 days, 1 cell was disassembled. Since all of the metallic lithium had disappeared completely, it was confirmed that a predetermined amount of lithium ions was previously doped into the negative electrode.
  • a charge / discharge cycle test was performed using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current and constant voltage (CC CV) charging method of 0.1V at 0.1C. The discharge was a constant current (CC) discharge method that ended when the voltage reached 3.0 V at 0.05C.
  • CC CV constant current and constant voltage
  • the discharge capacity after repeating charge and discharge three times under the above conditions was 5.4 Ah.
  • this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 127 Wh / kg-cell.
  • the positive electrode negative electrode operating potential when the cell was discharged at 0 V was determined from the reference electrode, and both were 0.3 V based on the metallic lithium.
  • Comparative Example 3 two battery cells were produced in the same manner as in Comparative Example 2, except that the thickness of the lithium metal disposed in the upper and lower two locations on the outermost part of the electrode laminate unit was changed to 140 m. Each cell was disassembled after being left for 20 days. Since all of the metallic lithium had disappeared completely, it was confirmed that a predetermined amount of lithium ions was previously doped into the negative electrode.
  • a charge / discharge cycle test was performed using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen). Discharging was a constant current (CC) discharging method that ended when it reached 0 V at 0.05C.
  • CC CV constant current constant voltage
  • the discharge capacity after repeating charging and discharging three times under the above conditions was 5.4 Ah.
  • this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 128 Wh / kg-cell.
  • the positive and negative electrode operating potentials were determined from the reference electrode, and both were 0.4V based on metallic lithium.
  • Comparative Example 4 one battery cell was produced in the same manner as in Comparative Example 2, except that no lithium metal was disposed on the outermost part of the electrode laminate unit.
  • a charge / discharge cycle test was performed using the produced one-cell battery. Charging was terminated after 30 hours with a constant current and constant voltage (CC CV) charging method of 0.1 and 4.1 yen. The discharge was a constant current (CC) discharge method that ended when it reached 3.0V at 0.05C.
  • CC CV constant current and constant voltage
  • the discharge capacity after repeating charging and discharging three times under the above conditions was 3.6 Ah.
  • the positive and negative electrode operating potentials were determined from the reference electrode, and both were 3.6V based on metallic lithium.
  • Example 3 The energy density of Example 3 is lower than that of the other examples, but the same positive electrode of Example 2 was used.
  • the positive electrode active material had a layer length of 5 nm or more and 25 nm or less, and more widely, a layer length of 1 nm or more and 30 nm or less. It was found that the direction energy density using vanadium pentoxide, in which layered fine crystal particles were randomly assembled, was used as the active material of the positive electrode was higher.
  • a graphite material was used for the negative electrode as a battery configuration.
  • the same effect can be obtained by using any negative electrode material that can be doped with lithium ion.
  • a tin alloy, a key alloy, or the like can be used.
  • the present invention is particularly effective in the field of positive electrode materials for large-capacity lithium secondary batteries.

Abstract

Provided is a novel crystalline structure for improving characteristic improvement effects of a vanadium oxide or the like as an electrode active material. The crystalline structure of a layer-like crystalline material such as vanadium oxide is mixedly in an amorphous state and a layer-like crystalline state at a prescribed ratio. In the layer-like crystalline structure, since a layer-like crystalline particle having a layer length (L1) of 30nm or less is formed, entry and coming out of ions into and from between the layers are facilitated. When such material is used as a positive electrode active material, a nonaqueous lithium secondary battery having excellent service capacity and cycle characteristics can be configured.

Description

明 細 書  Specification
リチウムイオン二次電池  Lithium ion secondary battery
技術分野  Technical field
[0001] 本発明は電池技術に関し、特に、非水系のリチウム二次電池に有効な技術である。  [0001] The present invention relates to battery technology, and is particularly effective for non-aqueous lithium secondary batteries.
背景技術  Background art
[0002] 近年、負極にグラフアイト等の炭素材料を用い、正極に LiCoO等のリチウム含有金 属酸化物を用いた、所謂リチウムイオン二次電池が提供されている。力、かるリチウムィ オン二次電池は、他の二次電池と比較して、高電圧及び高容量を有する為、蓄電装 置として、主にノート型パソコンや携帯電話の主電源として実用化されて!/、る。  [0002] In recent years, a so-called lithium ion secondary battery using a carbon material such as graphite for a negative electrode and a lithium-containing metal oxide such as LiCoO for a positive electrode has been provided. Because of its high voltage and capacity compared to other secondary batteries, KARU Li-ion secondary batteries have been put to practical use as power storage devices, mainly as the main power source for notebook computers and mobile phones. ! /
[0003] リチウムイオン二次電池は、電池組立後、充電することにより、正極のリチウム含有 金属酸化物から負極にリチウムイオンを供給し、放電では、負極のリチウムイオンを 正極に戻すという、いわゆるロッキングチェア型電池である。一般に、リチウムイオン 二次電池に用いられる正極材料と負極材料の充放電時におけるクーロン効率を比 較すると、正極材料のクーロン効率が負極材料のクーロン効率よりも高い。この場合、 組立後における電池の初期容量は、充電量と負極のクーロン効率の積となる。つまり 、電池の初期容量は、負極のクーロン効率により決定される。  [0003] A lithium ion secondary battery is a so-called locking in which, after battery assembly, charging is performed to supply lithium ions from a lithium-containing metal oxide of a positive electrode to the negative electrode, and in discharging, the lithium ions of the negative electrode are returned to the positive electrode. It is a chair type battery. In general, when comparing the Coulomb efficiency during charging and discharging of a positive electrode material and a negative electrode material used in a lithium ion secondary battery, the Coulomb efficiency of the positive electrode material is higher than the Coulomb efficiency of the negative electrode material. In this case, the initial capacity of the battery after assembly is the product of the charge amount and the coulomb efficiency of the negative electrode. That is, the initial capacity of the battery is determined by the Coulomb efficiency of the negative electrode.
[0004] このため、リチウムイオン二次電池の高エネルギー密度化を目指して、単位重量あ たりの放電容量が大きな負極材料、例えば Sn系の酸化物を用いても、負極のクーロ ン効率が低いと、電池の放電容量は小さくなる。現状のリチウムイオン二次電池では 、負極のクーロン効率が低い。よって、充填されている正極材料に対して 100%のエネ ルギーを使用できて!/、な!/、。  [0004] For this reason, even if a negative electrode material having a large discharge capacity per unit weight, such as a Sn-based oxide, is used with the aim of increasing the energy density of a lithium ion secondary battery, the coulomb efficiency of the negative electrode is low. As a result, the discharge capacity of the battery is reduced. In the current lithium ion secondary battery, the coulomb efficiency of the negative electrode is low. Therefore, 100% energy can be used for the positive electrode material filled! / ,!
[0005] また、リチウムイオン二次電池では、正極材料には LiCoO、 LiNiO、 LiMn 0に代 表される酸化物型化合物群、あるいは LiFePOに代表されるオリビン化合物群が広く  [0005] In addition, in lithium ion secondary batteries, positive electrode materials include a wide range of oxide-type compounds represented by LiCoO, LiNiO, LiMn 0, or olivine compounds represented by LiFePO.
4  Four
一般に使用されている。かかる構成では、正極材料中にリチウムイオンを含有する。 よって、負極と組み合わせるだけで、容易に二次電池として作動させることが可能と なる。  Generally used. In such a configuration, the positive electrode material contains lithium ions. Therefore, it can be easily operated as a secondary battery simply by combining with the negative electrode.
[0006] しかし、上記リチウム含有金属酸化物は、その酸化還元反応にお!/、て、リチウム含 有金属酸化物 1モル当たりの、リチウムイオンの利用量力 1モルを下回る。よって、 高レヽ放電容量を期待することができなレ、。 [0006] However, the lithium-containing metal oxide is used in the oxidation-reduction reaction! Less than 1 mole of lithium ion utilization per mole of metal oxide. Therefore, we cannot expect a high level discharge capacity.
[0007] 一方、バナジウム酸化物は、バナジウム酸化物 1モル当たり、数モルのリチウムィォ ンをドープ、あるいは脱ドープすること力 Sできる。よって、大容量のリチウムイオン二次 電池用正極材料となる可能性がある。例えば、特許文献 1、 2には、五酸化バナジゥ ム (V 0 )をゲル化させて合成したキセロゲルを、正極活物質として使用した技術が開 示されている。しかし、これらは、いずれも、結晶の充分発達したゲル状態の活物質 を使用している。さらに、活物質を、集電体上に直接形成させた薄膜電極である。よ つて、電子伝導性は低く特性を十分に発揮させることができなレ、。  [0007] On the other hand, vanadium oxide can dope or dedope several moles of lithium ion per mole of vanadium oxide. Therefore, it may become a positive electrode material for a large capacity lithium ion secondary battery. For example, Patent Documents 1 and 2 disclose a technique using xerogel synthesized by gelling vanadium pentoxide (V 0) as a positive electrode active material. However, all of them use an active material in a gel state in which crystals are sufficiently developed. Furthermore, it is a thin film electrode in which an active material is directly formed on a current collector. Therefore, the electron conductivity is low and the characteristics cannot be fully exhibited.
[0008] 特許文献 1、 2に開示の構成では、金属リチウムを使用した高分子固体電解質型の 電池構成としている。これにより、デンドライトリチウムの析出によるショートを回避して いる。しかし、かかる高分子固体電解質を用いても、長期間サイクル後のデンドライト 析出を抑制することは難しい。このため、特許文献 1、 2に開示の構成は、大容量電 源としての使用が困難である。  [0008] The configurations disclosed in Patent Documents 1 and 2 have a polymer solid electrolyte type battery configuration using metallic lithium. This avoids a short circuit due to the precipitation of dendrite lithium. However, even if such a polymer solid electrolyte is used, it is difficult to suppress dendrite precipitation after a long cycle. For this reason, the configurations disclosed in Patent Documents 1 and 2 are difficult to use as a large-capacity power source.
[0009] 特許文献 3には、炭素負極と液体電解質を用いた二次電池が開示されている。こ れは、正極とリチウム極を組み合わせて、正極に予めリチウムイオンをドープさせてお き、その後、リチウム極と炭素負極と組み替えて、電池を作製する。非特許文献 1には 、正極作動電位を 2.5V以上で運用する、同様の電池系での充放電に関する技術が 開示されている。  [0009] Patent Document 3 discloses a secondary battery using a carbon negative electrode and a liquid electrolyte. In this method, a positive electrode and a lithium electrode are combined, and the positive electrode is doped with lithium ions in advance, and then the lithium electrode and the carbon negative electrode are combined to produce a battery. Non-Patent Document 1 discloses a technique related to charge and discharge in a similar battery system that operates at a positive electrode operating potential of 2.5 V or more.
[0010] 一方、特許文献 4では、 V 0とリチウム塩とを熱処理することで、化学的に LiV 0を 合成している。これにより、予めリチウムイオンを補っている。  On the other hand, in Patent Document 4, LiV 0 is chemically synthesized by heat treating V 0 and a lithium salt. Thereby, lithium ions are supplemented in advance.
特許文献 1 :特許 3108186号公報  Patent Document 1: Japanese Patent No. 3108186
特許文献 2：特許 31 15448号公報  Patent Document 2: Japanese Patent No. 31 15448
特許文献 3 :特公平 5— 80791号公報  Patent Document 3: Japanese Patent Publication No. 5-80791
特許文献 4：特開平 05— 198300号公報  Patent Document 4: Japanese Patent Laid-Open No. 05-198300
非特許文献 l : Joumal of Power Sources 54(1995)146-150  Non-Patent Literature l: Joumal of Power Sources 54 (1995) 146-150
発明の開示  Disclosure of the invention
発明が解決しょうとする課題 [0011] ところ力 上記リチウムイオン二次電池の技術においては、以下の課題がある。すな わち、特許文献 3の技術では、リチウムイオン供給源が正極からのみである。よって、 負極の充放電効率によって制約を受け、高い放電エネルギーを引き出すことができ ない。また、リチウムイオンのドープェ程と、電極の組替え工程があるために、実際の 電池の生産に際しては生産性が低レ、。 Problems to be solved by the invention [0011] However, the above-described lithium ion secondary battery technology has the following problems. That is, in the technique of Patent Document 3, the lithium ion supply source is only from the positive electrode. Therefore, it is restricted by the charge / discharge efficiency of the negative electrode, and high discharge energy cannot be extracted. In addition, because there is a lithium ion doping process and an electrode recombination process, productivity is low when actually manufacturing batteries.
[0012] 非特許文献 1のように、 2.5V以上で運用すると、正極の利用率が低ぐ高工ネルギ 一密度を出すことが難しい。  [0012] As described in Non-Patent Document 1, when operating at 2.5 V or higher, it is difficult to achieve a high energy density with low utilization of the positive electrode.
[0013] 特許文献 4の技術では、予めリチウムイオンを、 V 0と Li塩とを熱処理することで、 化学的に補っている。この方法では、熱処理によって V 0と反応して取り込むことの できるリチウムイオンの量が限定される。よって、高い放電エネルギーを供給すること ができない。  [0013] In the technique of Patent Document 4, lithium ions are chemically supplemented by heat treating V 0 and a Li salt in advance. In this method, the amount of lithium ions that can be incorporated by reacting with V 0 by heat treatment is limited. Therefore, high discharge energy cannot be supplied.
[0014] 本発明の目的は、製造が容易で、高いエネルギー密度を有したリチウムイオン二次 電池を提供することにある。  An object of the present invention is to provide a lithium ion secondary battery that is easy to manufacture and has a high energy density.
[0015] 本発明の前記ならびにその他の目的と新規な特徴は、本明細書の記述および添 付図面から明らかになるであろう。 [0015] The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
課題を解決するための手段  Means for solving the problem
[0016] 本願において開示される発明のうち、代表的なものの概要を簡単に説明すれば、 次のとおりである。 [0016] Among the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.
[0017] 上記課題を解決するため、本発明者らは鋭意研究を行った結果、リチウムイオン二 次電池の正極、負極が、ある作動電位範囲内にあること力 高いエネルギー密度を 発現する上で重要となることを見出し、本発明に至った。  [0017] In order to solve the above problems, the present inventors have conducted intensive research. As a result, the positive electrode and the negative electrode of the lithium ion secondary battery are within a certain operating potential range. As a result, the present invention has been found.
[0018] すなわち、正極、負極、及び、リチウム塩と、非プロトン性有機溶媒からなる電解液 を備え、正極活物質力 Sリチウムイオン及び/又はァニオンを可逆的にドープ可能な 物質で、負極活物質がリチウムイオンを可逆的にドープ可能な物質で構成したリチウ ムイオン二次電池で、正極と負極を短絡させた後の正極及び負極電位が、金属リチ ゥム (対 Li/Li+)基準で 0.5V以上、 2.0V以下であるようにした。  [0018] That is, a positive electrode, a negative electrode, and an electrolyte solution comprising a lithium salt and an aprotic organic solvent, and a positive electrode active material strength S A material capable of reversibly doping lithium ions and / or anions, Lithium ion secondary battery made of a material that can be reversibly doped with lithium ions. The positive electrode and negative electrode potentials after short-circuiting the positive and negative electrodes are 0.5% on the basis of metal lithium (vs. Li / Li +). It was made to be V or more and 2.0V or less.
発明の効果  The invention's effect
[0019] 本願において開示される発明のうち、代表的なものによって得られる効果を簡単に 説明すれば以下のとおりである。 [0019] Among the inventions disclosed in the present application, the effects obtained by typical ones can be simply The description is as follows.
[0020] 非水系リチウムイオン二次電池で、正極、負極の作動電位を 0.5V以上、 2.0V以下 の範囲内とすることで、高いエネルギー密度を有するリチウムイオン二次電池を提供 する。例えば、本願請求項 2に示されるバナジウム酸化物を正極に用いた場合、電池 重量当たりのエネルギー密度力 ¾00Wh/kgを上回る、高いエネルギー密度を有するリ チウムイオン二次電池を提供する。 [0020] A lithium ion secondary battery having a high energy density is provided by setting the operating potential of the positive electrode and the negative electrode in the range of 0.5 V or more and 2.0 V or less in a non-aqueous lithium ion secondary battery. For example, when the vanadium oxide shown in claim 2 of the present application is used for a positive electrode, a lithium ion secondary battery having a high energy density exceeding an energy density power of ¾00 Wh / kg per battery weight is provided.
図面の簡単な説明  Brief Description of Drawings
[0021] [図 1]本発明のリチウムイオン二次電池の作動電位の状況を示す説明図である。  [0021] FIG. 1 is an explanatory diagram showing a situation of an operating potential of a lithium ion secondary battery of the present invention.
[図 2]本発明で使用される層長の短い層状結晶構造を模式的に示したアモルファス 化ゲルのイメージ図である。  FIG. 2 is an image diagram of an amorphized gel schematically showing a layered crystal structure with a short layer length used in the present invention.
[図 3]本発明で使用されるのとは異なる層長の長い層状結晶構造を模式的に示した ゲル化のイメージ図である。  FIG. 3 is an image diagram of gelation schematically showing a layered crystal structure having a long layer length different from that used in the present invention.
[図 4]本発明で使用される正極の活物質の X線回析パターンを示す説明図である。  FIG. 4 is an explanatory diagram showing an X-ray diffraction pattern of a positive electrode active material used in the present invention.
[図 5]本発明で使用され正極活物質の製造方法のフロー図である。  FIG. 5 is a flow diagram of a method for producing a positive electrode active material used in the present invention.
[図 6]本発明で使用され正極活物質の製造方法のフロー図である。  FIG. 6 is a flowchart of a method for producing a positive electrode active material used in the present invention.
[図 7]本発明で使用される正極活物質の透過型電子顕微鏡 (TEM)による図面代用 写真である。  FIG. 7 is a drawing-substituting photograph of a positive electrode active material used in the present invention by a transmission electron microscope (TEM).
[図 8]本発明の積層型のリチウムイオン二次電池の概略構成を模式的に示す説明図 である。  FIG. 8 is an explanatory view schematically showing a schematic configuration of a laminated lithium ion secondary battery of the present invention.
[図 9]本発明の捲回型のリチウムイオン二次電池の概略構成を模式的に示す説明図 である。  FIG. 9 is an explanatory view schematically showing a schematic configuration of a wound type lithium ion secondary battery of the present invention.
[図 10]本発明の折り畳み型のリチウムイオン二次電池の概略構成を模式的に示す説 明図である。  FIG. 10 is an explanatory view schematically showing a schematic configuration of a foldable lithium ion secondary battery of the present invention.
[図 11]本発明で使用される正極活物質の透過型電子顕微鏡 (TEM)による図面代 用写真である。  FIG. 11 is a drawing-substituting photograph of a positive electrode active material used in the present invention by a transmission electron microscope (TEM).
[図 12]本発明の効果を比較例とともに表形式で示した説明図である。  FIG. 12 is an explanatory diagram showing the effect of the present invention in a tabular format together with a comparative example.
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0022] 以下、本発明の実施の形態を図面に基づいて詳細に説明する。本発明は、リチウ ムイオン二次電池に関する技術である。力、かる技術において、本発明者は、前記の 如ぐリチウムイオン二次電池の正極、負極が、ある作動電位範囲内にあるときに高 いエネルギー密度を発現することを見出した。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention This is a technology related to muon secondary batteries. In this technology, the present inventor has found that the positive electrode and the negative electrode of the lithium ion secondary battery as described above exhibit a high energy density when they are within a certain operating potential range.
[0023] 本発明に係るリチウムイオン二次電池は、正極、負極、及び、リチウム塩と非プロト ン性有機溶媒からなる電解液を備える。また、正極活物質がレドッタス活性を示す金 属酸化物あるいは有機化合物である。また、負極活物質力 Sリチウムイオンを可逆的に ドープ可能な物質である。正極と負極を短絡させた後の正極及び負極電位が、金属 リチウム (対 Li/Li+)基準で 0.5V以上、 2.0V以下に設定する。これにより、リチウムィォ ン二次電池を高エネルギー化することができる。  [0023] A lithium ion secondary battery according to the present invention includes a positive electrode, a negative electrode, and an electrolytic solution composed of a lithium salt and a non-protonic organic solvent. Further, the positive electrode active material is a metal oxide or an organic compound exhibiting redox activity. In addition, the negative electrode active material strength S is a material that can be reversibly doped with lithium ions. The positive and negative electrode potentials after short-circuiting the positive and negative electrodes are set to 0.5 V or more and 2.0 V or less on the basis of metallic lithium (vs. Li / Li +). This can increase the energy of the lithium-ion secondary battery.
[0024] 上記レドックス活性を示す有機化合物としては、例として、アセチレン、ァニリン、テ トラチォナフタレン、チォフェン誘導体もしくはその重合体がある。  [0024] Examples of the organic compound exhibiting redox activity include acetylene, aniline, tetrathionaphthalene, thiophene derivatives, and polymers thereof.
[0025] 図 1に、リチウムイオン二次電池電位プロファイルを示した。図 1に示すように、リチウ ムイオン二次電池では、実際のセル電圧は、正極電位を示す曲線と、負極電位を示 す曲線との差し引き電位を示すセル電圧曲線で示される。すなわち、セル電圧 =正 極電位 負極電位となる。  FIG. 1 shows a potential profile of a lithium ion secondary battery. As shown in FIG. 1, in the lithium ion secondary battery, the actual cell voltage is indicated by a cell voltage curve indicating a subtraction potential between a curve indicating the positive electrode potential and a curve indicating the negative electrode potential. That is, cell voltage = positive electrode potential and negative electrode potential.
[0026] 力、かる正極電位の曲線と、負極電位の曲線と、が交わった点が、両極を短絡させた 0V放電時の正極、負極の電位となる。かかる正極、負極の電位が、金属リチウムィォ ン (対 Li/Li+)基準で 0.5V以上、 2.0V以下であること力 本発明の一つの大きな特徴で ある。図中、かかる範囲を矢印で示した。  [0026] The point at which the curve of the force, the positive electrode potential, and the negative electrode potential curve intersect is the potential of the positive electrode and the negative electrode during 0 V discharge when both electrodes are short-circuited. The potential of the positive electrode and the negative electrode is 0.5 V or more and 2.0 V or less on the basis of metal lithium ion (vs. Li / Li +). This is one major feature of the present invention. Such a range is indicated by an arrow in the figure.
[0027] 図 1に示すように、曲線 αが正極電位を示す場合には、容量は大きいが正極の利 用容量が少なぐエネルギー密度は小さくなる。一方、曲線 /3が正極電位を示す場 合には、正極の利用容量は十分だ力 負極の電位は 0.5V未満となり、負極の容量を 十分に利用できず、やはりエネルギー密度が小さくなる。よって、正極、負極の容量 を十分に利用できる範囲として、本発明では、上記 0.5V以上、 2.0V以下の範囲を設 定した。  [0027] As shown in FIG. 1, when the curve α indicates the positive electrode potential, the energy density is small, but the capacity is large but the positive electrode capacity is small. On the other hand, when curve / 3 indicates the positive electrode potential, the capacity of the positive electrode is sufficient. The potential of the negative electrode is less than 0.5 V, so that the capacity of the negative electrode cannot be fully utilized, and the energy density is also reduced. Therefore, in the present invention, the range of 0.5 V or more and 2.0 V or less is set as a range in which the capacity of the positive electrode and the negative electrode can be sufficiently utilized.
[0028] 力、かるリチウムイオン二次電池では、例えば、正極活物質として、層状結晶性物質 を有し、前記層状結晶性物質は、 0を含まない 30匪以下の層長の微細結晶粒子を有 することを特徴とする電極材料を用いるのが好ましい。さらに、負極材料としては、易 黒鉛化炭素材料 (soft carbon)、黒鉛、あるいは易黒鉛化炭素材料と黒鉛との混合物 を使用するのが好ましい。 [0028] In a lithium ion secondary battery, for example, it has a layered crystalline material as a positive electrode active material, and the layered crystalline material contains fine crystalline particles having a layer length of 30 mm or less not containing 0. It is preferable to use an electrode material characterized by having it. Furthermore, as a negative electrode material, easy It is preferable to use graphitized carbon material (soft carbon), graphite, or a mixture of graphitizable carbon material and graphite.
[0029] 力、かるリチウムイオン二次電池の電池構成としては、例えば、正極及び負極を、セ パレータを介して交互に積層した後に、捲回、折り畳み、または 3層以上積層された セル構成とするのが好ましレ、。 [0029] As a battery configuration of a lithium ion secondary battery, for example, a cell configuration in which positive electrodes and negative electrodes are alternately stacked via a separator and then wound, folded, or stacked in three or more layers is used. I prefer to do it.
[0030] かかる構成では、正極集電体及び負極集電体には、表面から裏面へと貫通する貫 通孔が設けられる。負極、あるいは正極、あるいは負極及び正極は、金属リチウムと の電気化学的接触により、予めリチウムイオンをドープされる。 In such a configuration, the positive electrode current collector and the negative electrode current collector are provided with through holes that penetrate from the front surface to the back surface. The negative electrode, or the positive electrode, or the negative electrode and the positive electrode are previously doped with lithium ions by electrochemical contact with metallic lithium.
[0031] 本発明において、ドープとは、吸蔵、担持、吸着または揷入をも意味し、正極活物 質にリチウムイオン及び/又はァニオンが入る現象、あるいは負極活物質にリチウム イオンが入る現象を意味する。脱ドープとは、放出、脱着をも意味し、正極活物質か らリチウムイオン又はァニオンが脱離する現象、あるいは負極活物質からリチウムィォ ンが脱離する現象をレ、うものとする。 In the present invention, dope means occlusion, support, adsorption or insertion, and refers to a phenomenon in which lithium ions and / or anions enter the positive electrode active material, or a phenomenon in which lithium ions enter the negative electrode active material. means. De-doping means release and desorption, and refers to a phenomenon in which lithium ions or anions are desorbed from the positive electrode active material, or a phenomenon in which lithium ions are desorbed from the negative electrode active material.
[0032] ァニオンのドープとは、正極側にポリアセチレン、ポリア二リン等の導電性高分子を 用いた場合に、電解質中に含まれる支持塩のァニオンがドープされることを言う。例 えば、 CF SO—、 C F SO―、 (CF SO ) N―、 (CF SO ) C―、 BF―、 PF―、 CIO—がドープさ [0032] The term "anion doping" means that an anion of a supporting salt contained in an electrolyte is doped when a conductive polymer such as polyacetylene or polyaniline is used on the positive electrode side. For example, CF SO-, C F SO-, (CF SO) N-, (CF SO) C-, BF-, PF-, CIO- are doped.
3 3 4 9 8 3 2 2 3 2 3 4 6 4  3 3 4 9 8 3 2 2 3 2 3 4 6 4
れることを言う。  Say that.
[0033] 力、かる構成を有する本発明のリチウムイオン二次電池について、以下、さらに詳細 に説明する。本発明で用いる正極用の活物質としては、例えば、従来のリチウムィォ ン二次電池で用いられる LiCoO 、 LiNiO 、 LiMn 0に代表される酸化物型化合物群 、 LiFePOに代表されるオリビン化合物群が利用可能である。あるいは層状結晶性物  [0033] The lithium ion secondary battery of the present invention having such a configuration will be described in further detail below. As the active material for the positive electrode used in the present invention, for example, an oxide type compound group represented by LiCoO, LiNiO, and LiMn 0 used in a conventional lithium-ion secondary battery, or an olivine compound group represented by LiFePO is used. Is possible. Or layered crystalline material
4  Four
質のバナジウム酸化物、特に五酸化バナジウムが利用可能である。  Quality vanadium oxides, in particular vanadium pentoxide, are available.
[0034] 本発明における層状結晶性物質の状態とは、匪以下のオーダで観察するミクロ的 な視点では、層長が 30nm以下の結晶構造のみ、もしくは層長が 30匪以下の結晶構 造とアモルファス構造とが、共存している状態のことを言う。かかる状態を、例えばェ ックス線回折分析で得られるような nmより大きい、 μ mオーダ以上で観察するマクロ 的な視点から見た場合には、結晶構造がランダムに配列した見かけ上アモルファス 構造が観察される。 [0035] かかる五酸化バナジウムを、マクロ的に見かけ上アモルファス化することで、層状結 晶性物質の層長を短く (微細化)する。例えば、層長が長い層状結晶状態が、分断さ れて、層長の短い層状結晶状態が出現する。 [0034] The state of the layered crystalline substance in the present invention refers to a crystal structure having a layer length of 30 nm or less or a crystal structure having a layer length of 30 mm or less from a microscopic viewpoint observed on the order of 匪 or less. It means a state where an amorphous structure coexists. When such a state is viewed from a macroscopic viewpoint, such as that obtained by X-ray diffraction analysis, which is larger than nm and is observed on the order of μm or more, an apparently amorphous structure in which crystal structures are randomly arranged is observed. Is done. [0035] By making the vanadium pentoxide macroscopically amorphous, the layer length of the layered crystalline substance is shortened (miniaturized). For example, a layered crystal state with a long layer length is divided, and a layered crystal state with a short layer length appears.
[0036] かかる状態は、アモルファス状態になっていては実現できない、新規な構造である 。アモルファス化の進行状態を、途中で止めることにより、上記状態、すなわち層長の 短い層状結晶状態が存在できるようになる。  [0036] Such a state is a novel structure that cannot be realized in an amorphous state. By stopping the progress of the amorphization halfway, the above state, that is, a layered crystal state with a short layer length can exist.
[0037] 図 2には、本発明に係る層長 L1の短い層状結晶状態、すなわち見かけ上のァモル ファス化状態を、模式的に示した。力、かる見かけ上のアモルファス化状態では、層長 L1が平均的に短い周期で繰り返す所謂短周期構造が、層状結晶構造を構成してい る。本発明に係る見かけ上のアモルファス化状態では、このように短周期構造の層状 結晶が、複数集合している。  [0037] FIG. 2 schematically shows a layered crystal state having a short layer length L1 according to the present invention, that is, an apparent amorphized state. In a force or apparently amorphous state, a so-called short-period structure in which the layer length L1 repeats with a short period on average forms a layered crystal structure. In the apparently amorphized state according to the present invention, a plurality of layered crystals having a short period structure are thus assembled.
[0038] 一方、従来例では、図 3に示すように、層長 L2が平均的に長い周期で繰り返す、所 謂長周期構造の層状結晶状態が得られる。  On the other hand, in the conventional example, as shown in FIG. 3, a layered crystal state having a so-called long-period structure in which the layer length L2 repeats with an average long period is obtained.
[0039] 本発明に係る層長が短い層状結晶状態を、例えば、電池の電極活物質として使用 すると、電池の反応等に関与するイオン等の化学種が、層状結晶状態の層間に出入 りし易くなる。例えば、層間にドープされたイオンは、層長が短いため、その拡散パス が短くなり、拡散し易くなる。イオンの出入りが円滑に行われない、前記長周期構造 の層状結晶状態の場合に比べて、充放電特性あるレヽはサイクル耐性等が優れてレ、  [0039] When the layered crystal state according to the present invention having a short layer length is used as, for example, an electrode active material of a battery, chemical species such as ions involved in the reaction of the battery enter and exit between layers in the layered crystal state. It becomes easy. For example, ions doped between layers have a short layer length, so that their diffusion path is short and they are easily diffused. Compared with the layered crystalline state of the long-period structure in which ions do not enter and exit smoothly, the layer with charge / discharge characteristics has excellent cycle resistance and the like.
[0040] かかる構成では、特に層長の長さが重要である。かかる層長は、イオンの出入りに 際して、直接的にイオンが通過する経路 (パス）の長さに影響を与える。勿論、層長以 外の部分も、例えば、層状結晶構造の層の厚さ方向の長さも、平均結晶粒子が小さ くなるに従って、小さくなつても構わない。要は、層状結晶構造の間に結晶粒子が小 さくなり、全体的にはイオンの出入りがし易い状態となることが重要である。 [0040] In such a configuration, the length of the layer length is particularly important. Such a layer length affects the length of a path through which ions pass directly when ions enter and exit. Of course, the portion other than the layer length, for example, the length in the thickness direction of the layer of the layered crystal structure may be reduced as the average crystal grain becomes smaller. In short, it is important that the crystal grains become smaller between the layered crystal structures, and that the ions can easily enter and exit as a whole.
[0041] 前記層長の短い層状結晶状態は、原料に酸化バナジウムを用いて、これを過酸化 水素 0 )やアルカリ塩で溶解させ、さらにこの溶解液を固化することで、好適に作 製することが可能である。  [0041] The layered crystal state having a short layer length is preferably produced by using vanadium oxide as a raw material, dissolving it with hydrogen peroxide 0) or an alkali salt, and further solidifying the solution. It is possible.
[0042] H 0を用いた場合、溶解した酸化バナジウム溶解液は酸性を呈する。アルカリ塩を 用いた場合、アルカリ性を呈する。 [0042] When H 0 is used, the dissolved vanadium oxide solution is acidic. Alkali salt When used, it exhibits alkalinity.
[0043] アルカリ塩のカチオン源としてリチウムイオンを用いた場合、合成段階で、酸化バナ ジゥム中に、リチウムイオンをドープさせることが出来る。 When lithium ions are used as the cation source for the alkali salt, lithium ions can be doped into the vanadium oxide at the synthesis stage.
[0044] これらいずれの溶液からも、溶媒を除去することで、好適にアモルファス状態の酸 化バナジウムを作製することが出来る。 [0044] By removing the solvent from any of these solutions, it is possible to suitably produce amorphous vanadium oxide.
[0045] リチウムイオン源としては、例えば、水溶性の硫化リチウム、水酸化リチウム、セレン 化リチウム、あるいはテルル化リチウム等が利用可能である。力、かるリチウム化合物の 群から選ばれた少なくとも 1種のリチウム化合物を、水溶性リチウムイオン源として用 いること力 Sでさる。 [0045] As the lithium ion source, for example, water-soluble lithium sulfide, lithium hydroxide, lithium selenide, lithium telluride, or the like can be used. The power S is to use at least one lithium compound selected from the group of such lithium compounds as a water-soluble lithium ion source.
[0046] 上記バナジウム酸化物を合成する際に、硫黄含有有機導電性ポリマーに対応する モノマーを活物質に混合させる場合がある。ただし、最終的な正極活物質としては硫 黄含有有機導電性ポリマーに対応するモノマーを除去することが望ましい。詳細は 不明であるが、バナジウム酸化物の合成反応時に、酸化物組成を維持する上で、硫 黄含有有機導電性ポリマーは機能しているが、活物質としての性能は低いと考えら れる。  [0046] When the vanadium oxide is synthesized, a monomer corresponding to the sulfur-containing organic conductive polymer may be mixed with the active material. However, it is desirable to remove the monomer corresponding to the sulfur-containing organic conductive polymer as the final positive electrode active material. Although details are unknown, the sulfur-containing organic conductive polymer is functioning in maintaining the oxide composition during the synthesis reaction of vanadium oxide, but the performance as an active material is considered to be low.
[0047] 力、かる非水系のリチウムイオン二次電池用の正極材料の活物質では、その活物質 に含まれる金属酸化物の X線回折パターンは、図 4に示すように、回折角 2 Θ =5〜15 ° の範囲にのみピークを有している。  [0047] In the active material of the positive electrode material for a non-aqueous lithium ion secondary battery, the X-ray diffraction pattern of the metal oxide contained in the active material has a diffraction angle of 2 Θ, as shown in FIG. It has a peak only in the range of = 5 to 15 °.
[0048] このようにして得られる活物質を、ポリフッ化ビニリデン（PDVF)等のバインダと、好 ましくは導電性粒子と共に混合して正極用の材料とする。これを導電性の基体 (集電 体）上に塗布して、正極を作製する。非水系のリチウムイオン二次電池用の正極材料 の層は、例えば 10〜200 μ mの厚さに形成する。  [0048] The active material thus obtained is mixed with a binder such as polyvinylidene fluoride (PDVF), preferably with conductive particles, to obtain a positive electrode material. This is applied on a conductive substrate (current collector) to produce a positive electrode. The layer of the positive electrode material for the non-aqueous lithium ion secondary battery is formed to a thickness of 10 to 200 μm, for example.
[0049] 上記導電性粒子としては、導電性カーボン (ケッチェンブラック等の導電性カーボン 等）、銅、鉄、銀、ニッケル、パラジウム、金、白金、インジウム、タングステン等の金属 、酸化インジウム、酸化スズ等の導電性金属酸化物等がある。力、かる導電性粒子は、 上記金属酸化物の重量の 1〜30%の割合で含まれていればよい。  [0049] The conductive particles include conductive carbon (conductive carbon such as ketjen black), metal such as copper, iron, silver, nickel, palladium, gold, platinum, indium, tungsten, indium oxide, oxide There are conductive metal oxides such as tin. The conductive particles may be contained in an amount of 1 to 30% of the weight of the metal oxide.
[0050] 正極材料を支持する基体 (集電体）には、少なくとも正極材料と接する表面にお!/、 て導電性を有する導電性基体が使用できる。かかる基体は、金属、導電性金属酸化 物、導電性カーボン等の導電性材料で形成することができる。特に、銅、金、アルミ二 ゥム、あるいはそれらの合金、または導電性カーボンが好ましい。また、基体を非導 電性材料で形成した場合には、その基体を導電性材料で被覆することが必要である [0050] For the substrate (current collector) that supports the positive electrode material, a conductive substrate having conductivity at least on the surface in contact with the positive electrode material can be used. Such a substrate is a metal, conductive metal oxide Or a conductive material such as conductive carbon. In particular, copper, gold, aluminum, an alloy thereof, or conductive carbon is preferable. In addition, when the base is formed of a non-conductive material, it is necessary to coat the base with a conductive material.
[0051] 力、かる非水系リチウム二次電池の正極材料として有効な、短い層長を有する層状 結晶性物質は、図 5のフロー図に示すような製造工程を経て製造される。 [0051] A layered crystalline substance having a short layer length, which is effective as a positive electrode material for a non-aqueous lithium secondary battery, is manufactured through a manufacturing process as shown in the flowchart of FIG.
[0052] 図 5に示すように、ステップ S110で、層状結晶性物質として、例えば、五酸化バナ ジゥムを準備する。併せて、ステップ S 120で水溶性のリチウムイオン源を、ステップ S 130で硫黄含有有機導電性に対応するモノマーを準備する。  [0052] As shown in FIG. 5, in step S110, for example, vanadium pentoxide is prepared as a layered crystalline material. In addition, a water-soluble lithium ion source is prepared in step S120, and a monomer corresponding to sulfur-containing organic conductivity is prepared in step S130.
[0053] ステップ S140で、ステップ S 110 S120 S130で準備した五酸化バナジウム、水 溶性リチウムイオン源、硫黄含有有機導電性ポリマーに対応するモノマーを、水に懸 濁する。力、かる懸濁によりアモルファス化が始まる。水溶性リチウムイオン源としては、 例えば、硫化リチウム、水酸化リチウムを使用可能である。硫黄含有有機導電性に対 応するモノマーには、例えば、 3, 4—エチレンジォキシチォフェンが使用可能である  [0053] In step S140, the monomers corresponding to vanadium pentoxide prepared in steps S110, S120, and S130, the water-soluble lithium ion source, and the sulfur-containing organic conductive polymer are suspended in water. Amorphization begins with force and suspension. As the water-soluble lithium ion source, for example, lithium sulfide or lithium hydroxide can be used. For example, 3,4-ethylenedioxythiophene can be used as the monomer corresponding to the sulfur-containing organic conductivity.
[0054] かかる懸濁液を、ステップ S 150で所定時間加熱還流させる。ステップ S 150の加熱 還流後は、ステップ S160でろ過することで、加熱還流した懸濁液から、固形分を除 去する。固形分を除去したろ液は、ステップ S170で濃縮される。ろ液の濃縮後、ステ ップ S 180で、真空乾燥等により乾燥させる。 [0054] The suspension is heated to reflux in step S150 for a predetermined time. After heating and refluxing in step S150, the solid content is removed from the heated and refluxed suspension by filtering in step S160. The filtrate from which the solid content has been removed is concentrated in step S170. After concentrating the filtrate, it is dried in step S 180 by vacuum drying or the like.
[0055] その後、ステップ S 190で、ボールミル等により所定粒径に粉砕し、篩い分けを行つ て分級する。このようにして、五酸化バナジウムの層長の短い層状結晶構造粉末が 得られる。かかる層状結晶構造粉末を、正極材料の活物質として使用する。  [0055] Thereafter, in step S190, the particles are pulverized to a predetermined particle size by a ball mill or the like, and classified by sieving. In this way, a layered crystal structure powder having a short layer length of vanadium pentoxide is obtained. Such layered crystal structure powder is used as an active material of the positive electrode material.
[0056] 但し、ステップ S 150 S 180の工程で、加熱処理を行う場合、加熱温度を 250°C未 満で行う必要がある。 250°Cを超えると、層長の短い層状結晶が変化するので、好ま しくない。  [0056] However, when heat treatment is performed in steps S 150 S 180, the heating temperature needs to be less than 250 ° C. If it exceeds 250 ° C, the layered crystals with a short layer length change, which is not preferable.
[0057] 力、かる短い層長を有する層状結晶性物質は、図 6のフロー図に示すような製造ェ 程を経てあ製造すること力 Sでさる。  [0057] A layered crystalline substance having a force and such a short layer length can be manufactured by a manufacturing force S as shown in the flow diagram of FIG.
[0058] 図 6に示すように、ステップ S210で、非水系リチウムイオン二次電池の正極材料用 の活物質を合成する。所要の材料を水に混合して、所定時間加熱還流することで、 水に可溶な活物質を合成する。このようにして合成した、正極材料用の活物質の懸 濁液を濾過して、ステップ S220で、噴霧乾燥法を適用する。かかる噴霧乾燥法を適 用することで、正極材料用の活物質を、微細な球状粒子の正極材料粉末とすること ができる。かかる正極材料粉末は、平均粒子径が 0.1 m以上、 20 m以下の球状 の水溶性粒子である。 [0058] As shown in FIG. 6, in step S210, for the positive electrode material of the non-aqueous lithium ion secondary battery. Synthesize active material. A necessary material is mixed with water and heated to reflux for a predetermined time to synthesize an active material soluble in water. The active material suspension for the positive electrode material synthesized in this way is filtered, and in step S220, the spray drying method is applied. By applying this spray drying method, the active material for the positive electrode material can be made into a fine spherical particle positive electrode material powder. The positive electrode material powder is a spherical water-soluble particle having an average particle diameter of 0.1 m or more and 20 m or less.
[0059] 噴霧乾燥法を用いることなぐ一旦生成した活物質を、図 5に示すように、ボールミ ル等により所定粒径に粉砕し、篩い分けを行って分級することも可能である。し力、し、 噴霧乾燥法を適用することで、粉砕、分級等の手間が省け、さらには、得られる粒子 が平均粒径の細かいサブミクロン以下の球状粒子となる。このようにして、五酸化バ ナジゥム等のバナジウム酸化物の、層長の短い層状結晶構造粉末が得られる。  [0059] As shown in Fig. 5, the active material once produced without using the spray drying method may be pulverized to a predetermined particle size with a ball mill or the like and classified by sieving. By applying the spraying and drying method, it is possible to save the troubles of pulverization, classification, etc., and further, the obtained particles become fine spherical particles having a fine average particle diameter of submicron or less. In this way, a layered crystal structure powder of vanadium oxide such as vanadium pentoxide having a short layer length is obtained.
[0060] 上記製造工程では、加熱処理を行う場合には、加熱温度を 250°C未満で行う必要 がある。 250°Cを超えると、層長の短い本発明の層状結晶が変化するので好ましくな い。  [0060] In the above manufacturing process, when the heat treatment is performed, it is necessary to perform the heating at a temperature of less than 250 ° C. If it exceeds 250 ° C, the layered crystal of the present invention having a short layer length changes, which is not preferable.
[0061] 本発明の層状結晶性物質では、断面で観察される結晶粒子において、層長が 30η m以下の層状結晶状態が、その断面における面積率で 30%以上含まれていることが 好ましい。例えば、任意の断面での結晶粒子が、面積％で30%以上含まれていれば好 ましい。  [0061] In the layered crystalline substance of the present invention, it is preferable that the crystal grains observed in the cross section include a layered crystal state having a layer length of 30 ηm or less in an area ratio of 30% or more in the cross section. For example, it is preferable that crystal grains in an arbitrary cross section are contained in an area of 30% or more.
[0062] 力、かる構成のリチウムイオン二次電池のエネルギー密度は、結晶粒子力 ¾0nmを超 える層長の層状結晶構造を含む場合より、良好である。また、面積％で30%以上、 100% 未満含まれていればよい。上限は限りなく 100%に近い値まで有効である。尚、 100%の 場合には、結晶粒子中には、アモルファス状態は存在せず、層状結晶状態のみとな  [0062] The energy density of the lithium ion secondary battery having such a structure is better than that of the case where it includes a layered crystal structure having a layer length exceeding the crystal particle force of> 0 nm. Further, it may be contained in an area% of 30% or more and less than 100%. The upper limit is valid up to a value close to 100%. In the case of 100%, there is no amorphous state in the crystal particles, and only the layered crystal state.
[0063] 層状結晶構造の最小の層長は、 1匪以上が好ましい。層状結晶の層長が 1匪未満 であると層状構造が維持できないためにリチウムイオンのドープ、脱ドープができず、 容量を取り出すことができない。逆に層長が 30匪を超えると、充放電に伴う結晶構造 の崩壊が起こり、サイクル特性が悪くなる。そこで、層長は、 lnm以上 30nm以下である ことが好ましい。より好ましくは、層長が 5nm以上 25nm以下である。 [0064] 図 7には、層長が lnm以上、 30nm以下である、本発明で使用する正極活物質の層 状結晶状態を、図面代用写真として使用する透過型電子顕微鏡写真で示した。例え ば、図 7は、リチウム 五酸化バナジウムの場合で、特に 5nm以上、 25nmの層状結晶 の状態が見られる場合である。 [0063] The minimum layer length of the layered crystal structure is preferably 1 mm or more. If the layer length of the layered crystal is less than 1 mm, the layered structure cannot be maintained, so lithium ions cannot be doped or dedoped, and the capacity cannot be taken out. On the other hand, if the layer length exceeds 30 mm, the crystal structure collapses due to charge and discharge, resulting in poor cycle characteristics. Therefore, the layer length is preferably 1 nm or more and 30 nm or less. More preferably, the layer length is 5 nm or more and 25 nm or less. FIG. 7 shows a layered crystal state of the positive electrode active material used in the present invention having a layer length of 1 nm or more and 30 nm or less as a transmission electron micrograph used as a drawing substitute photo. For example, Fig. 7 shows the case of lithium vanadium pentoxide, especially when a layered crystal state of 5 nm or more and 25 nm is observed.
[0065] かかる活物質を用いて正極を形成することで、非水系リチウムイオン二次電池を構 成する。非水系リチウムイオン二次電池は、上記正極と、負極と、上記正極と負極の 間に配置された電解質層を備えた構成である。  [0065] A non-aqueous lithium ion secondary battery is formed by forming a positive electrode using such an active material. The non-aqueous lithium ion secondary battery includes the positive electrode, the negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode.
[0066] 力、かる構成の非水系リチウムイオン二次電池において、負極は、通常使用されてい るリチウムイオン二次電池用の材料が利用可能である。力、かる材料としては、金属リ チウムゃリチウム合金（例えば Li-Al合金）のようなリチウム系金属材料、スズゃケィ素 のような金属とリチウム金属との金属間化合物材料、窒化リチウムのようなリチウム化 合物、またはリチウムインターカレーシヨン炭素材料を挙げることができる。  [0066] In a non-aqueous lithium ion secondary battery having such a configuration, a commonly used material for a lithium ion secondary battery can be used for the negative electrode. Examples of the power and curable materials include lithium-based metal materials such as lithium metal lithium alloys (eg, Li-Al alloys), intermetallic compound materials of metals and lithium metals such as tin-cathenium, and lithium nitride. And a lithium intercalation carbon material.
[0067] また、電解質としては、 CF SO Li、 C F SO Li、 (CF SO ) NLi、 (CF SO ) CLi、 LiBF  [0067] As electrolytes, CF SO Li, C F SO Li, (CF SO) NLi, (CF SO) CLi, LiBF
3 3 4 9 8 3 2 2 3 2 3 4 3 3 4 9 8 3 2 2 3 2 3 4
、 LiPF、 LiCIO等のリチウム塩が使用可能である。力、かる電解質を溶解する溶媒はLithium salts such as LiPF and LiCIO can be used. The solvent that dissolves power and electrolytes
6 4 6 4
非水系溶媒である。  It is a non-aqueous solvent.
[0068] 非水系溶媒としては、鎖状カーボネート、環状カーボネート、環状エステル、二トリ ル化合物、酸無水物、アミド化合物、ホスフェート化合物、ァミン化合物等が利用可 能である。具体的には、エチレンカーボネート（EC)、ジェチルカーボネート（DEC) 、プロピレンカーボネート、ジメトキシェタン、 Ί ブチロラタトン、 η メチノレピロリジノ ン、 Ν, N'—ジメチルァセトアミド、ァセトニトリル、あるいはプロピレンカーボネートと ジメトキシェタンとの混合物、スルホランとテトラヒドロフランとの混合物等である。 [0068] As the non-aqueous solvent, chain carbonates, cyclic carbonates, cyclic esters, nitrile compounds, acid anhydrides, amide compounds, phosphate compounds, amine compounds, and the like can be used. Specifically, ethylene carbonate (EC), jetyl carbonate (DEC), propylene carbonate, dimethoxyethane, Ίbutyrolatathone, η methinolepyrrolidinone, Ν, N'-dimethylacetamide, acetonitrile, or propylene carbonate And a mixture of dimethoxyethane and a mixture of sulfolane and tetrahydrofuran.
[0069] 正極と負極との間に介揷される電解質層としては、上記電解質を非水系溶媒に溶 解させた溶液が利用可能である。あるいは、力、かる電解質溶液を含むポリマーゲル（ ポリマーゲル電解質）が利用可能である。  [0069] As the electrolyte layer interposed between the positive electrode and the negative electrode, a solution obtained by dissolving the above electrolyte in a non-aqueous solvent can be used. Alternatively, a polymer gel (polymer gel electrolyte) containing a force, electrolyte solution can be used.
[0070] かかる非水系リチウム二次電池は、例えば、図 8に示すような構成である。すなわち 、非水系リチウム二次電池 10では、負極 1と、正極 2とが、セパレータ 3を介して対向 する。負極 1は、負極活物質が、集電体としての基体面に、層状に設けられている。 正極 2は、正極活物質が、集電体としての基体面に、層状に設けられている。 [0071] かかる負極 1と正極 2とが、図 8に示すように、セパレータ 3を介して、複数が積層さ れる。図 8に示す構成では、上下方向に積層され、上下端が、負極 1となる。かかる上 下端に形成された負極 1には、セパレータ 3を介して、金属リチウム 4が積層される。 Such a non-aqueous lithium secondary battery has a configuration as shown in FIG. 8, for example. That is, in the nonaqueous lithium secondary battery 10, the negative electrode 1 and the positive electrode 2 face each other with the separator 3 interposed therebetween. In the negative electrode 1, a negative electrode active material is provided in a layered manner on a substrate surface as a current collector. In the positive electrode 2, a positive electrode active material is provided in a layered manner on a substrate surface as a current collector. A plurality of such negative electrodes 1 and positive electrodes 2 are laminated via separators 3 as shown in FIG. In the configuration shown in FIG. 8, the upper and lower ends are stacked in the vertical direction, and the negative electrode 1 is formed at the upper and lower ends. Metallic lithium 4 is laminated on the negative electrode 1 formed on the upper and lower ends via a separator 3.
[0072] 金属リチウム 4の外側は、集電体としての銅メッシュ 5で覆われて!/、る。図示はしな!/ヽ 1S かかる積層された電極群が、上記電解質を溶解した非水系溶媒中に設けられて いる。あるいは、上記電解質を溶解した非水系溶媒を、セパレータ 3に含浸させてあ  [0072] The outside of the metallic lithium 4 is covered with a copper mesh 5 as a current collector! Not shown! / ヽ 1S Such a stacked electrode group is provided in a non-aqueous solvent in which the electrolyte is dissolved. Alternatively, the separator 3 is impregnated with a non-aqueous solvent in which the electrolyte is dissolved.
[0073] 非水系のリチウムイオン二次電池の構成は、他の構成でも構わない。例えば、捲回 、あるいは折り畳んだ構成でも構わない。図 9に示す構成は、捲回型の構成である。 図 10に示す構成は、折り畳んだ構成である。 [0073] The configuration of the non-aqueous lithium ion secondary battery may be other configurations. For example, it may be a wound or folded configuration. The configuration shown in FIG. 9 is a wound configuration. The configuration shown in FIG. 10 is a folded configuration.
[0074] 尚、本発明で開発した正極材料は、正極材料 1モルに対して、数モルのリチウムィ オンをドープさせることができる。ただし、ある量を超えると、脱ドープ能力が著しく低 下する。このしきい値は、リチウム金属に対して 1.45Vまでである。これを下回ると容量 劣化が進行する。これ以上であれば、高い充放電容量とサイクル性能を両立させるこ とができる。好ましくは 1.45V以上から 2V、より好ましくは 1.5Vから 1.9Vである。  [0074] The positive electrode material developed in the present invention can be doped with several moles of lithium ions per mole of the positive electrode material. However, beyond a certain amount, the dedoping ability is significantly reduced. This threshold is up to 1.45V for lithium metal. Below this, capacity degradation proceeds. If it is more than this, it is possible to achieve both high charge / discharge capacity and cycle performance. Preferably it is 1.45V or more to 2V, more preferably 1.5V to 1.9V.
実施例  Example
[0075] (実施例 1) [0075] (Example 1)
正極活物質の作製：本実施例では、図 6のステップ S210で、 50gの V 0に 51の 10% Preparation of positive electrode active material: In this example, in step S210 of FIG.
H 0を室温で添加した。生成した赤橙色の V 0ゾル溶液を、ステップ S220で、ガス 吹き出し口温度 225°C、排気口温度 110°Cの乾燥雰囲気中に、送液速度 12ml/minで 四流体ノズルより噴霧し、その後 150°Cで真空乾燥した。これにより、赤橙色の粉末 45 gを得た。 H 0 was added at room temperature. The generated red-orange V 0 sol solution is sprayed from a four-fluid nozzle at a liquid feed rate of 12 ml / min in a dry atmosphere at a gas outlet temperature of 225 ° C and an exhaust outlet temperature of 110 ° C in step S220. Vacuum dried at 150 ° C. This gave 45 g of a red-orange powder.
[0076] TG (熱天秤、 Thermo-Gravimetry)から、この粉末の組成を求めた。 V 0 -0.3H Ou.  [0076] The composition of this powder was determined from TG (Thermobalance, Thermo-Gravimetry). V 0 -0.3H Ou.
組成であった。また、 CuK a線源を用いた XRD(X線回析)にお!/、て、 2 Θ =7° 付近に 001面に帰属される弱い回折線が観測された。また、 SEM (走査電子顕微鏡)におけ る観察の結果、球状粒子が認められた。この粒子のレーザー回折散乱法による粒度 分布計測の結果、 D90は lO rnであった。また TEM分析において、図 11に示すよ うに、層長力^〜 10nmの層状の微結晶粒子がランダム方向に存在していることが観測 された。 TEM像の観察視野内で面積当たりの層状結晶粒子の割合は、 100%と見積 もられた。 It was a composition. In addition, weak diffraction lines attributed to the 001 plane were observed around 2 Θ = 7 ° in XRD (X-ray diffraction) using a CuKa source. As a result of observation by SEM (scanning electron microscope), spherical particles were observed. As a result of measuring the particle size distribution of this particle by the laser diffraction scattering method, D90 was lO rn. In TEM analysis, as shown in Fig. 11, it was observed that layered microcrystalline particles with a layer strength of ~ 10 nm existed in random directions. It was done. The ratio of layered crystal particles per area within the observation field of the TEM image was estimated to be 100%.
[0077] 正極の作製：上記正極活物質と、導電助材としてカーボンブラックと、バインダとし てポリフッ化ビニリデン（PVDF)とを、重量比 90: 5 : 5で混合し、 n—メチルピロリドン（N MP)で希釈してスラリーを調製した。力、かるスラリーを、貫通孔を有するアルミニウム 製集電体（基体）両面に均一に塗布した。 150°Cで減圧乾燥した後、プレスし、厚み 2 49 μ mの正極を得た。  [0077] Fabrication of positive electrode: The above positive electrode active material, carbon black as a conductive additive, and polyvinylidene fluoride (PVDF) as a binder were mixed at a weight ratio of 90: 5: 5, and n-methylpyrrolidone (N A slurry was prepared by dilution with (MP). The slurry was applied uniformly on both sides of the aluminum current collector (substrate) having through holes. After drying under reduced pressure at 150 ° C., pressing was performed to obtain a positive electrode having a thickness of 249 μm.
[0078] 負極の作製：表面を不活性処理した市販の天然黒鉛と、バインダとして PVDFとを、 重量比 94 : 6で混合し、 NMPで希釈したスラリーを調製した。力、かるスラリーを、貫通 孔を有する銅製集電体の両面または片面に均一に塗布した。これを成型し、両面負 極の厚み力 ¾39 a m、片面負極の厚み力 S 127 μ mの負極を得た。  [0078] Production of negative electrode: Commercially available natural graphite whose surface was subjected to inert treatment and PVDF as a binder were mixed at a weight ratio of 94: 6, and a slurry diluted with NMP was prepared. The slurry was applied uniformly on both sides or one side of the copper current collector having through holes. This was molded to obtain a negative electrode having a thickness power of ¾39 am of the double-sided negative electrode and a thickness force S of 127 μm of the single-sided negative electrode.
[0079] 電池の作製：上記のようにして作製した正極を、 92mm X 76mmに、また負極を 96mm  [0079] Production of battery: The positive electrode produced as described above was 92 mm x 76 mm, and the negative electrode was 96 mm.
X 79mmにそれぞれ裁断した。正極を 16枚と負極を 17枚（内片面塗布 2枚）を、セパレ ータとしてポリオレフイン系微多孔膜を介して積層した。正極の未塗工部にアルミユウ ム端子を溶接し、負極の未塗工部に Ni端子を溶接して電極積層ユニットを構成した  Cut to X 79mm respectively. Sixteen positive electrodes and 17 negative electrodes (two coated on the inner side) were laminated as separators through a polyolefin microporous membrane. An aluminum laminated terminal was welded to the uncoated part of the positive electrode, and an Ni terminal was welded to the uncoated part of the negative electrode to form an electrode laminate unit.
[0080] 電極積層ユニット最外部に、セパレータを介して、負極集電体に圧着した厚さ 500 [0080] A thickness of 500 bonded to the negative electrode current collector through a separator on the outermost part of the electrode lamination unit
fi mのリチウム金属を、上下 2箇所に配置し、正極、負極、金属リチウムおよびセパレ ータからなる極群を構成した。また、金属リチウムの集電体と負極集電体は溶接した  Fim lithium metal was placed in two locations, upper and lower, to form a pole group consisting of a positive electrode, a negative electrode, metallic lithium, and a separator. The metallic lithium current collector and the negative electrode current collector were welded.
[0081] lmol/1でホウフッ化リチウム（LiBF )を溶解したエチレンカーボネート/ジェチルカ [0081] Ethylene carbonate / Jetylca with lithium borofluoride (LiBF) dissolved at lmol / 1
4  Four
ーボネート = 1 /3 (重量比）の電解液を注入した。続いて金属リチウムを圧着した極 群近傍を、 Niワイア一に固定し、正極及び負極の電位をモニターする参照極とした。 開口部を熱溶着により封止した。このようにして、電池セルを 2セル作製した。  An electrolyte solution of boronate = 1/3 (weight ratio) was injected. Subsequently, the vicinity of the electrode group to which metal lithium was crimped was fixed to the Ni wire, and used as a reference electrode for monitoring the potential of the positive electrode and the negative electrode. The opening was sealed by heat welding. In this way, two battery cells were produced.
[0082] リチウムイオンのドープ工程：上記のようにして作製した電池を、 20日間放置した後  [0082] Lithium ion doping step: After the battery prepared as described above was left for 20 days
1セルを分解した。分解したセルでは、金属リチウムはいずれも完全に消失していた 。このこと力、ら、所定量のリチウムイオンが予め負極にドープされたことを確認した。  1 cell was disassembled. In the decomposed cell, all metallic lithium was completely lost. For this reason, it was confirmed that a predetermined amount of lithium ions was previously doped into the negative electrode.
[0083] 充放電試験：残りの 1セルの電池を用いて、充放電サイクル試験を行った。充電は 0 .1Cで 4.1Vの定電流一定電圧（CC CV)充電方式で、 30時間後に終了とした。放 電は 0.05Cで 0Vになった時点で終了する定電流（CC)放電方式とした。前記条件で 充放電を 3回繰り返した後、正極、負極の作動電位を、参照極より求めた。ともに金属 リチウム基準で 1.5Vであった。 [0083] Charging / discharging test: A charging / discharging cycle test was performed using the remaining one-cell battery. 0 charge It was terminated after 30 hours with a constant current and constant voltage (CC CV) charging method of 4.1V at .1C. The discharge was a constant current (CC) discharge method that ended when it reached 0V at 0.05C. After charging and discharging three times under the above conditions, the operating potentials of the positive electrode and the negative electrode were determined from the reference electrode. Both were 1.5V based on metallic lithium.
[0084] また、このときの放電容量は 13.5Ahとなった。これを、参照極を除レ、た電池質量で 割り付けて電池重量当たりに換算したところ、図 12に示すように、 223Wh/kg-cellとな つた。 [0084] The discharge capacity at this time was 13.5 Ah. When this was assigned by the battery mass excluding the reference electrode and converted per battery weight, it was 223 Wh / kg-cell as shown in FIG.
[0085] (実施例 2)  [0085] (Example 2)
本実施例では、正極、負極の構成は実施例 1と同様にし、電極積層ユニット最外部 の上下 2箇所に配置した金属リチウムの厚さを 490 a mに変更した。それ以外の構成 は、実施例 1と同様に電池セルを構成し、 2セル作製した。 20日間放置した後、 1セル を分解したところ、金属リチウムはいずれも完全に消失していたことから、所定量のリ チウムイオンが予め負極にドープされたことを確認した。  In this example, the configuration of the positive electrode and the negative electrode was the same as in Example 1, and the thickness of the metallic lithium disposed at the upper and lower two locations on the outermost part of the electrode laminate unit was changed to 490 am. Other than that, battery cells were constructed in the same manner as in Example 1, and two cells were produced. When the cell was disassembled after being left for 20 days, all of the lithium metal had disappeared, so it was confirmed that a predetermined amount of lithium ion was previously doped into the negative electrode.
[0086] 残りの 1セルの電池を用いて、充放電サイクル試験を行った。充電は0.1(：で4.1¥の 定電流一定電圧（CC CV)充電方式で 30時間後に終了とした。放電は 0.05Cで 0V になった時点で終了する定電流（CC)放電方式とした。  [0086] A charge / discharge cycle test was performed using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen). Discharging was a constant current (CC) discharging method that ended when it reached 0 V at 0.05C.
[0087] 前記条件で充放電を 3回繰り返した後、正極、負極の作動電位を参照極より求めた 。ともに金属リチウム基準で 2.0Vとなった。このときの放電容量は 12.7Ahとなった。こ れを、参照極を除いた電池質量で割り付けて電池重量当たりに換算したところ、図 1 2に示すように、 201Wh/kg-cellとなった。  [0087] After charging and discharging three times under the above conditions, the operating potentials of the positive electrode and the negative electrode were determined from the reference electrode. Both became 2.0V based on metallic lithium. The discharge capacity at this time was 12.7 Ah. When this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 201 Wh / kg-cell as shown in FIG.
[0088] (実施例 3)  [0088] (Example 3)
本実施例では、正極の構成、負極の構成、金属リチウムの厚さの構成を除いて、実 施例 1と同様に構成した。  In this example, the configuration was the same as Example 1 except for the configuration of the positive electrode, the configuration of the negative electrode, and the configuration of the thickness of metallic lithium.
[0089] 正極の作製：市販の LiCo02と、導電助材としてグラフアイトと、バインダとしてポリフ ッ化ビ二リデン（PVDF)とを、重量比 91:5:4で混合し、 n メチルピロリドン（NMP)で 希釈してスラリーを調製した。力、かるスラリーを、貫通孔を有するアルミニウム製集電 体両面に均一に塗布した。 150°Cで減圧乾燥した後、プレスし、厚み 183 mの正極 を得た。 [0090] 負極の作製：表面を不活性処理した市販の天然黒鉛と、バインダとして PVDFとを、 重量比 94 : 6で混合し、 NMPで希釈したスラリーを調製した。このスラリーを、貫通孔 を有する銅製集電体両面または片面に均一に塗布した。これを成型し、両面負極の 厚みが 239 H m、片面負極の厚みが 127 μ mの負極を得た。 [0089] Fabrication of positive electrode: Commercially available LiCo02, graphite as a conductive additive, and polyvinylidene fluoride (PVDF) as a binder were mixed at a weight ratio of 91: 5: 4, and n-methylpyrrolidone (NMP ) To prepare a slurry. The slurry was applied uniformly on both sides of the aluminum current collector having through holes. After drying under reduced pressure at 150 ° C., pressing was performed to obtain a positive electrode having a thickness of 183 m. [0090] Production of negative electrode: A commercially available natural graphite whose surface was subjected to inert treatment and PVDF as a binder were mixed at a weight ratio of 94: 6, and a slurry diluted with NMP was prepared. This slurry was uniformly applied to both sides or one side of a copper current collector having through holes. This was molded to obtain a negative electrode having a double-sided negative electrode thickness of 239 Hm and a single-sided negative electrode thickness of 127 μm.
[0091] 電池の作製：上記正極及び負極を用いて、リチウムイオン二次電池を構成した。か かる電池構成では、電極積層ユニット最外部の上下 2箇所に配置した金属リチウムの 厚さを 85 mに変更した以外は、実施例 1と同様である。このようにして、電池セルを 2セル作製した。 20日間放置した後、 1セルを分解したところ、金属リチウムはいずれ も完全に消失してレ、たことから、所定量のリチウムイオンが予め負極に吸蔵されたこと を確認した。  [0091] Fabrication of battery: A lithium ion secondary battery was constructed using the positive electrode and the negative electrode. Such a battery configuration is the same as that of Example 1 except that the thickness of the metallic lithium disposed at the upper and lower two positions on the outermost part of the electrode stack unit is changed to 85 m. In this way, two battery cells were produced. When the cell was disassembled after being left for 20 days, all of the lithium metal disappeared and it was confirmed that a predetermined amount of lithium ions had previously been occluded in the negative electrode.
[0092] 残りの 1セルの電池を用いて、充放電サイクル試験を行った。充電は0.1(：で4.1¥の 定電流一定電圧（CC CV)充電方式で 30時間後に終了とした。放電は 0.05Cで 3.0 [0092] A charge / discharge cycle test was performed using the remaining one-cell battery. Charging was completed after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen at 3.0. Discharge was 3.0 at 0.05C.
Vになった時点で終了する定電流（CC)放電方式とした。 A constant current (CC) discharge method that ends when V is reached was adopted.
[0093] 前記条件で充放電を 3回繰り返した後の放電容量は、図 12に示すように、 5.4Ahと なった。これを、参照極を除いた電池質量で割り付けて電池重量当たりに換算したと ころ、 157Wh/kg-cellとなった。 [0093] As shown in FIG. 12, the discharge capacity after charging and discharging three times under the above conditions was 5.4 Ah. When this was allocated based on the battery mass excluding the reference electrode and converted per battery weight, it was 157 Wh / kg-cell.
[0094] また、セルを 0Vまで放電した際、前記正極 '負極作動電位を参照極より求めたとこ ろ、ともに金属リチウム基準で 0.5Vとなった。 Further, when the cell was discharged to 0 V, the positive electrode negative electrode operating potential was determined from the reference electrode, and both were 0.5 V based on metallic lithium.
[0095] (実施例 4) [Example 4]
正極活物質の作製：本実施例では、五酸化バナジウム 200gと、硫化リチウム (Li2S)30 g及び 3,4-エチレンジォキシチォフェン (EDOT)lOOgを水 5リットル中に懸濁し、 24時間 加熱攪拌還流を行った。攪拌終了後、吸引ろ過を行い、固形分を除去した。この固 形分は硫黄と 3,4-エチレンジォキシチォフェンの重合物であった。  Preparation of positive electrode active material: In this example, 200 g of vanadium pentoxide, 30 g of lithium sulfide (Li2S) and 3,4-ethylenedioxythiophene (EDOT) lOOg were suspended in 5 liters of water for 24 hours. The mixture was heated and stirred under reflux. After completion of the stirring, suction filtration was performed to remove the solid content. This solid was a polymer of sulfur and 3,4-ethylenedioxythiophene.
[0096] ろ液を 75°C、 10.67kPa(80Torr)の圧力で減圧濃縮し、水と有機物を除去することで 、黒色の固体を得た。この生成物を 100°Cで真空乾燥を行った。 TEM分析において 、図 7に示すように、層長が 5nm以上、 25nm以下の層状の微結晶粒子がランダム方 向に存在していることが観測された。 TEM像の観察視野内で、面積当たりのァモル ファス部に対する層状結晶粒子の割合は 100%と見積もられた。 [0097] 正極の作製：実施例 1と同様の組成で正極ペーストを調整し、貫通孔を有するアル ミニゥム製集電体の両面に塗工し、厚み 175 mの正極を作製した。 [0096] The filtrate was concentrated under reduced pressure at 75 ° C and a pressure of 10.67 kPa (80 Torr), and water and organic substances were removed to obtain a black solid. The product was vacuum dried at 100 ° C. In TEM analysis, as shown in FIG. 7, it was observed that layered microcrystalline particles having a layer length of 5 nm or more and 25 nm or less were present in a random direction. Within the observation field of the TEM image, the ratio of the layered crystal particles to the amorphous portion per area was estimated to be 100%. [0097] Production of positive electrode: A positive electrode paste was prepared with the same composition as in Example 1, and applied to both surfaces of an aluminum current collector having through-holes to produce a positive electrode having a thickness of 175 m.
[0098] 電池の作製:本実施例の上記正極と、前記実施例 1の負極を用いる以外は、実施 例 1と同様に、正極 16枚と負極 17枚並びにセパレータを用いて極群を構成して、ラミ ネート型の電池を作製した。  [0098] Fabrication of battery: In the same manner as in Example 1, except that the positive electrode of the present example and the negative electrode of Example 1 were used, the electrode group was composed of 16 positive electrodes, 17 negative electrodes, and a separator. Thus, a laminate type battery was produced.
[0099] リチウムイオンのドープ工程：上記のようにして作製した電池を、 20日間放置した後 、 1セルを分解した。金属リチウムはいずれも完全に消失していたことから、必要量の リチウムイオンが予め負極にドープされたことを確認した。  [0099] Lithium ion doping step: The battery prepared as described above was allowed to stand for 20 days, and then one cell was disassembled. Since all of the metallic lithium had disappeared completely, it was confirmed that the required amount of lithium ions was previously doped into the negative electrode.
[0100] 充放電試験： 1セルの電池を用いて、充放電サイクル試験を行った。充電は 0.1Cで  [0100] Charge / Discharge Test: A charge / discharge cycle test was performed using a battery of 1 cell. Charging at 0.1C
4. IVの定電流 定電圧（CC CV)充電方式で 30時間後に終了とした。放電は 0.05 Cで 0Vになった時点で終了する定電流（CC)放電方式とした。  4. IV constant current Constant voltage (CC CV) charging method was completed after 30 hours. The discharge was a constant current (CC) discharge method that ended when it reached 0 V at 0.05 C.
[0101] 前記条件で充放電を 3回繰り返した後の正極 ·負極作動電位を参照極より求めた。  [0101] The positive electrode / negative electrode operating potential after repeating charging and discharging three times under the above conditions was determined from the reference electrode.
ともに 1.5Vとなった。また、このときの放電容量は、図 12に示すように、 13.5Ahとなつ た。これを、参照極を除いた電池質量で割り付けて、電池重量当たりに換算したとこ ろ、 220Wh/kg-cellとなった。  Both became 1.5V. The discharge capacity at this time was 13.5 Ah as shown in FIG. When this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 220 Wh / kg-cell.
[0102] (比較例 1)  [0102] (Comparative Example 1)
比較例 1では、上記実施例 1で構成のリチウムイオン二次電池で、電極積層ユニット 最外部の上下 2箇所に配置した金属リチウムの厚さを 420 a mに変更した以外は、実 施例 1と同様に電池セルを 2セル作製した。 20日間放置した後、 1セルを分解した。 金属リチウムはいずれも完全に消失していたことから、所定量のリチウムイオンが予め 負極に吸蔵されたことを確認した。  Comparative Example 1 is the same as in Example 1 except that the lithium ion secondary battery configured in Example 1 above was changed to 420 am in the thickness of the metallic lithium disposed at the upper and lower two positions on the outermost part of the electrode stack unit. Similarly, two battery cells were produced. After leaving for 20 days, 1 cell was disassembled. Since all of the metallic lithium had disappeared completely, it was confirmed that a predetermined amount of lithium ions had previously been occluded in the negative electrode.
[0103] 残りの 1セルの電池を用いて、充放電サイクル試験を行った。充電は0.1(：で4.1¥の 定電流一定電圧（CC CV)充電方式で 30時間後に終了とした。放電は 0.05Cで 0V になった時点で終了する定電流（CC)放電方式とした。  [0103] A charge / discharge cycle test was conducted using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen). Discharging was a constant current (CC) discharging method that ended when it reached 0 V at 0.05C.
[0104] 前記条件で充放電を 3回繰り返した後の正極、負極作動電位を、参照極より求めた 。ともに金属リチウム基準で 2.1Vとなった。また、このときの放電容量は、図 12に示す ように、 10.3Ahとなった。これを、参照極を除いた電池質量で割り付けて、電池重量 当たりに換算したところ、 170Wh/kg-cellとなった。 [0105] (比較例 2) [0104] The positive electrode and negative electrode operating potentials after charging and discharging were repeated three times under the above conditions were determined from the reference electrode. Both were 2.1V based on metallic lithium. The discharge capacity at this time was 10.3 Ah as shown in FIG. When this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 170 Wh / kg-cell. [0105] (Comparative Example 2)
比較例 2では、実施例 2での正極、実施例 1での負極を用いて、電池を構成した。電 極積層ユニット最外部の上下 2箇所に配置したリチウム金属の厚さを 350 mに変更 した以外は、実施例 1と同様に、電池セルを 2セル作製した。 20日間放置した後、 1 セルを分解した。金属リチウムはいずれも完全に消失していたことから、所定量のリチ ゥムイオンが予め負極にドープされたことを確認した。  In Comparative Example 2, a battery was constructed using the positive electrode in Example 2 and the negative electrode in Example 1. Two battery cells were produced in the same manner as in Example 1, except that the thickness of the lithium metal disposed at the upper and lower two locations on the outermost part of the electrode laminate unit was changed to 350 m. After leaving it for 20 days, 1 cell was disassembled. Since all of the metallic lithium had disappeared completely, it was confirmed that a predetermined amount of lithium ions was previously doped into the negative electrode.
[0106] 残りの 1セルの電池を用いて、充放電サイクル試験を行った。充電は 0.1Cで 4.2Vの 定電流一定電圧（CC CV)充電方式で 30時間後に終了とした。放電は 0.05Cで 3.0 Vになった時点で終了する定電流（CC)放電方式とした。  [0106] A charge / discharge cycle test was performed using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current and constant voltage (CC CV) charging method of 0.1V at 0.1C. The discharge was a constant current (CC) discharge method that ended when the voltage reached 3.0 V at 0.05C.
[0107] 前記条件で充放電を 3回繰り返した後の放電容量は、図 12に示すように、 5.4Ahと なった。これを、参照極を除いた電池質量で割り付けて、電池重量当たりに換算した ところ、 127Wh/kg-cellとなった。また、セルを 0V放電した際の正極'負極作動電位を 、参照極より求めたところ、ともに金属リチウム基準で 0.3Vとなった。  [0107] As shown in FIG. 12, the discharge capacity after repeating charge and discharge three times under the above conditions was 5.4 Ah. When this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 127 Wh / kg-cell. The positive electrode negative electrode operating potential when the cell was discharged at 0 V was determined from the reference electrode, and both were 0.3 V based on the metallic lithium.
[0108] (比較例 3)  [0108] (Comparative Example 3)
比較例 3では、電極積層ユニット最外部の上下 2箇所に配置したリチウム金属の厚さ を 140 mに変更した以外は、比較例 2と同様に電池セルを 2セル作製した。 20日間 放置した後、各 1セルを分解した。金属リチウムはいずれも完全に消失していたことか ら、所定量のリチウムイオンが予め負極にドープされたことを確認した。  In Comparative Example 3, two battery cells were produced in the same manner as in Comparative Example 2, except that the thickness of the lithium metal disposed in the upper and lower two locations on the outermost part of the electrode laminate unit was changed to 140 m. Each cell was disassembled after being left for 20 days. Since all of the metallic lithium had disappeared completely, it was confirmed that a predetermined amount of lithium ions was previously doped into the negative electrode.
[0109] 残りの 1セルの電池を用いて、充放電サイクル試験を行った。充電は0.1(：で4.1¥の 定電流一定電圧（CC CV)充電方式で 30時間後に終了とした。放電は 0.05Cで 0V になった時点で終了する定電流（CC)放電方式とした。  [0109] A charge / discharge cycle test was performed using the remaining one-cell battery. Charging was terminated after 30 hours with a constant current constant voltage (CC CV) charging method of 0.1 (: 4.1 yen). Discharging was a constant current (CC) discharging method that ended when it reached 0 V at 0.05C.
[0110] 前記条件で充放電を 3回繰り返した後の放電容量は、図 12に示すように、 5.4Ahと なった。これを、参照極を除いた電池質量で割り付けて、電池重量当たりに換算した ところ、 128Wh/kg-cellとなった。また、セルを 0Vまで放電した際の、正極、負極作動 電位を、参照極より求めたところ、ともに金属リチウム基準で 0.4Vとなった。  [0110] As shown in FIG. 12, the discharge capacity after repeating charging and discharging three times under the above conditions was 5.4 Ah. When this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 128 Wh / kg-cell. In addition, when the cell was discharged to 0V, the positive and negative electrode operating potentials were determined from the reference electrode, and both were 0.4V based on metallic lithium.
[0111] (比較例 4)  [0111] (Comparative Example 4)
比較例 4では、電極積層ユニット最外部にリチウム金属を配置しない以外は、比較例 2と同様に電池セルを 1セル作製した。 [0112] 作製した 1セルの電池を用いて、充放電サイクル試験を行った。充電は0.1じで4.1¥ の定電流一定電圧（CC CV)充電方式で 30時間後に終了とした。放電は 0.05Cで 3 .0Vになった時点で終了する定電流（CC)放電方式とした。 In Comparative Example 4, one battery cell was produced in the same manner as in Comparative Example 2, except that no lithium metal was disposed on the outermost part of the electrode laminate unit. [0112] A charge / discharge cycle test was performed using the produced one-cell battery. Charging was terminated after 30 hours with a constant current and constant voltage (CC CV) charging method of 0.1 and 4.1 yen. The discharge was a constant current (CC) discharge method that ended when it reached 3.0V at 0.05C.
[0113] 前記条件で充放電を 3回繰り返した後の放電容量は、図 12に示すように、 3.6Ahと なった。これを、参照極を除いた電池質量で割り付けて、電池重量当たりに換算した ところ、 87Wh/kg-cellとなった。また、セルを 0Vまで放電した際の、正極'負極作動電 位を、参照極より求めたところ、ともに金属リチウム基準で 3.6Vとなった。  [0113] As shown in FIG. 12, the discharge capacity after repeating charging and discharging three times under the above conditions was 3.6 Ah. When this was allocated by the battery mass excluding the reference electrode and converted per battery weight, it was 87 Wh / kg-cell. In addition, when the cell was discharged to 0V, the positive and negative electrode operating potentials were determined from the reference electrode, and both were 3.6V based on metallic lithium.
[0114] 上記比較例 1〜4の結果からは、短絡後での非水系のリチウムイオン二次電池の作 動電位が、金属リチウム基準で、 0.4V、 0.3V等のように 0.5Vを下回る場合は、ェネル ギー密度が低くなることが確認された。また、 2. IV、 3.6Vと 2.0Vを超えても、エネルギ 一密度が減少することが確認された。一方、実施例;!〜 4に示すように、作動電位が 0 • 5V、 1.5V、 2.0Vのように、 0.5V以上、 2.0V以下にあれば、エネルギー密度が良好な ことが確認された。  [0114] From the results of the above Comparative Examples 1 to 4, the operating potential of the non-aqueous lithium ion secondary battery after short circuit is less than 0.5V, such as 0.4V, 0.3V, etc., based on metallic lithium In this case, it was confirmed that the energy density was lowered. In addition, it was confirmed that the energy density decreased even if it exceeded 2.IV, 3.6V and 2.0V. On the other hand, as shown in Examples;! To 4, it was confirmed that the energy density was good when the operating potential was 0.5 V or more and 2.0 V or less, such as 0 • 5 V, 1.5 V, or 2.0 V. .
[0115] 実施例 3のエネルギー密度は、他の実施例よりも低いが、同じ実施例 2の正極を用 [0115] The energy density of Example 3 is lower than that of the other examples, but the same positive electrode of Example 2 was used.
V、た比較例 2〜4と比較して高!/、値である。 V, high compared to Comparative Examples 2-4! /, Value.
[0116] すなわち、 0Vまで放電した際の正極電位が 2.0V (対 Li/Li+)を越える場合は、正極 材料の利用容量が不充分であると考えられる。また、 0.5Vを下回る場合は、正極材料 の利用容量は充分であるものの、負極材料の利用容量が不充分と考えられる。 That is, when the positive electrode potential when discharged to 0 V exceeds 2.0 V (vs. Li / Li +), it is considered that the available capacity of the positive electrode material is insufficient. On the other hand, when the voltage is less than 0.5 V, the available capacity of the positive electrode material is sufficient, but the available capacity of the negative electrode material is considered insufficient.
[0117] 従って、実施例;!〜 4の結果に示されるように、 0Vまで放電した際の正極電位が 0.5Accordingly, as shown in the results of Examples;! To 4, the positive electrode potential when discharged to 0 V was 0.5
V以上、 2.0V (対 Li/Li+)以下の範囲にあるものは、正極材料、負極材料ともに利用容 量が充分であるためエネルギー密度が高くなつたものと考えられる。 Those in the range of V or more and 2.0V (vs. Li / Li +) are considered to have increased energy density because the use capacity is sufficient for both the positive electrode material and the negative electrode material.
[0118] また、実施例 1、 2、 4と実施例 3の結果を比較することにより、正極活物質としては、 層長が 5nm以上、 25nm以下、より広くは層長が lnm以上 30nm以下の層状の微細結 晶粒子がランダムに集合した五酸化バナジウムを正極の活物質に用いた方力 エネ ルギー密度はより高くなることがわ力、つた。 [0118] Further, by comparing the results of Examples 1, 2, and 4 with Example 3, the positive electrode active material had a layer length of 5 nm or more and 25 nm or less, and more widely, a layer length of 1 nm or more and 30 nm or less. It was found that the direction energy density using vanadium pentoxide, in which layered fine crystal particles were randomly assembled, was used as the active material of the positive electrode was higher.
[0119] 以上、本発明者によってなされた発明を実施の形態に基づき具体的に説明したが[0119] While the invention made by the present inventor has been specifically described based on the embodiment,
、本発明は前記実施の形態に限定されるものではなぐその要旨を逸脱しない範囲 で種々変更可能であることはレ、うまでもなレ、。 [0120] 本発明では、電池構成として負極にグラフアイト材料を用いた。ただし、リチウムィォ ンをドープ可能な負極材料であればどのような材料を用いても同様の効果が得られ る。具体的には、スズ合金、ケィ素合金などが利用可能である。 The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. [0120] In the present invention, a graphite material was used for the negative electrode as a battery configuration. However, the same effect can be obtained by using any negative electrode material that can be doped with lithium ion. Specifically, a tin alloy, a key alloy, or the like can be used.
産業上の利用可能性  Industrial applicability
[0121] 本発明は、特に大容量リチウム二次電池の正極材料の分野で、有効である。 [0121] The present invention is particularly effective in the field of positive electrode materials for large-capacity lithium secondary batteries.

Claims

請求の範囲 The scope of the claims
[1] 正極、負極、及び、リチウム塩と非プロトン性有機溶媒からなる電解液を備え、正極 活物質がレドッタス活性を示す金属酸化物あるいは有機化合物であり、負極活物質 カリチウムイオンを可逆的にドープ可能な物質であるリチウムイオン二次電池であつ て、  [1] A positive electrode, a negative electrode, and an electrolyte solution composed of a lithium salt and an aprotic organic solvent, and the positive electrode active material is a metal oxide or organic compound exhibiting redox activity. Lithium ion secondary battery, a material that can be doped,
前記正極と前記負極を短絡させた後の正極及び負極電位が、金属リチウム基準で The positive electrode and negative electrode potential after short-circuiting the positive electrode and the negative electrode are based on metallic lithium.
、 0.5V以上、 2.0V以下 (対 Li/Li+)である、 0.5V or more, 2.0V or less (vs. Li / Li +),
ことを特徴とするリチウムイオン二次電池。  The lithium ion secondary battery characterized by the above-mentioned.
[2] 請求項 1記載のリチウムイオン二次電池において、 [2] The lithium ion secondary battery according to claim 1,
前記正極活物質が層状結晶性物質であり、前記層状結晶性物質は、 0を含まない 3 Onm以下の層長の微細結晶粒子を有するバナジウム酸化物である、  The positive electrode active material is a layered crystalline material, and the layered crystalline material is a vanadium oxide having fine crystal particles having a layer length of 3 Onm or less not containing 0.
ことを特徴とするリチウムイオン二次電池。  The lithium ion secondary battery characterized by the above-mentioned.
[3] 請求項 2記載のリチウムイオン二次電池において、 [3] The lithium ion secondary battery according to claim 2,
前記微細結晶粒子は、前記層状結晶性物質の断面で観察される面積率が 30%以 上、 100%以下の範囲である、  The fine crystal particles have an area ratio observed in a cross section of the layered crystalline material of 30% or more and 100% or less.
ことを特徴とするリチウムイオン二次電池。  The lithium ion secondary battery characterized by the above-mentioned.
[4] 請求項 1〜3のいずれ力、 1項に記載のリチウムイオン二次電池において、 [4] The lithium ion secondary battery according to any one of claims 1 to 3,
前記負極活物質が、易黒鉛化炭素材料、あるいは黒鉛、あるいは易黒鉛化炭素材 料と黒鉛である、  The negative electrode active material is a graphitizable carbon material, or graphite, or a graphitizable carbon material and graphite,
ことを特徴とするリチウムイオン二次電池。  The lithium ion secondary battery characterized by the above-mentioned.
[5] 請求項 1〜4のいずれ力、 1項に記載のリチウムイオン二次電池において、 [5] The lithium ion secondary battery according to any one of claims 1 to 4,
前記正極及び前記負極が、セパレータを介して交互に積層され、かつ捲回、あるい は折り畳み、あるレ、は 3層以上積層されたセル構成を有して!/、る、  The positive electrode and the negative electrode are alternately stacked via separators, and have a cell configuration in which three or more layers are stacked!
ことを特徴とするリチウムイオン二次電池。  The lithium ion secondary battery characterized by the above-mentioned.
[6] 請求項 1〜5のいずれ力、 1項に記載のリチウムイオン二次電池において、 [6] The lithium ion secondary battery according to any one of claims 1 to 5,
正極集電体及び負極集電体は貫通孔を有し、  The positive electrode current collector and the negative electrode current collector have through holes,
前記負極、あるいは前記正極、あるいは前記負極と前記正極とは、リチウムイオン 力 Sドープされている、 ：とを特徴とするリチウムイオン二次電池。 The negative electrode, or the positive electrode, or the negative electrode and the positive electrode are doped with lithium ion force S, A lithium ion secondary battery characterized by:
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